A C T A P A L A E O N T O L O G I C A P O L O N I C AVol. V 1960 No. 3

ANNA STASIŃSKA

VELUMBRELLA CZARNOCKII N. GEN., N. SP. - A LOWER CAMBRIAN JELLYFISH FROM THE HOLY CROSS MOUNTAINS Abstract. - Jan Czarnocki, a leading investigator of the geology of the Holy Cross Mountains (Góry Świętokrzyskie), discovered in 1927 imprints of fossil Jellyfish in the Lower Cambrian of the Brzechów area.The collection left by Czarnocki includes 118 more or less fragmentary individuals. These jellyfish are attributed to a single species described here as Velumbrella czarnockii n. gen., n. sp. This form is especially reminiscent of Ediacaria Sprigg of the Lower Cambrian of Australia. Both seem to belong to the Trachymedusae or Limnomedusae.

INTRODUCTION In the Lower Cambrian sandstones of Brzechów, in the Holy Cross Mountains, fossils resembling jellyfish have been found by the eminent Polish geologist Jan Czarnocki (1927). He provisionally placed these in the genus Medusites, distinguishing three species: M. gigas, M. brzechowiensis and Medusites sp. In an unpublished manuscript (1941), Czarnocki gave them a new generic name, Brzechowia, and listed only two species: Brzechowia brzechowiensis and Brzechowia sp. The two papers by this author are devoid of descriptions and illustrations. The names listed are therefore nomina nuda. In addition, as the names proposed by Czarnocki are difficult to pronounce for foreign readers, here I introduce a new name, Velumbrella czarnockii, to designate the form provisionally named by Czarnocki as Brzechowia brzechowiensis. I am unable to determine more precisely the form called Brzechowia sp. by Czarnocki. It probably corresponds to incomplete imprints visible in the vicinity of Velumbrella czarnockii (pl.I, fig. 1 and 2). Professor Roman Kozłowski drew my attention to these fossils.I am happy to express my deep gratitude to him, for it was thanks to his initiative that I undertook this study.

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Only part of the material collected by Czarnocki remains, having been rescued from the rubble of the Geological Institute, which was burned during the war. It is now in the museum of the Institute in Warsaw. The material was loaned to me for study, and I wish to express my gratitude to Dr. Mrs. M. Że1ichowska, curator and director of the Prof. E. Rühle Institute. I wish to thank Mrs. K. Pawłowska, daughter of J. Czarnocki, for the loan of her father's handwritten notes, and the information she provided me.

GENERAL CHARACTERISTICS OF THE LOWER CAMBRIAN STRATA OF THE HOLY CROSS MOUNTAINS

The Lower Cambrian of the Holy Cross Mountains is composed of clastic deposits of terrigenous origin (shale, quartz, greywacke, quartzite and sandstones). Based on the rich fauna, principally trilobites, it has been divided into several levels grouped into two new series: the lower and upper. The fauna of the lower series appears to contain Scandinavian forms. The fauna of the upper series has a more cosmopolitan character and reflects the relationships with distant parts of the North Atlantic province. Velumbrella czarnockii is found in the upper series represented by two Protolenus horizons (the CI f and CI g series).

The sandstones containing the jellyfish are composed of quartz grains from 0.18 to 0.24 mm in diameter. There are also some larger grains, 0.8 to 1.3 mm diameter. All grains are well rounded. The cement is composed of a clay substance that often fills cracks in the larger quartz grains. In addition to quartz, the sandstone contains fragments of siliceous rocks and occasionally thin flakes of muscovite. Accessory minerals seen in thin section include tourmaline, and zircon and rutile found as inclusions in quartz.

SYSTEMATIC PALAEONTOLOGY

Velumbrella n. gen.

Derivatio nominis: velum - sail, umbrella - small parasol; Medusoid possessing a clear velum. Diagnosis. - Because genus is represented by a single species, the diagnosis of the genus is provisionally the same as that of the species.

(TRANSLATED) VELUMBRELLA CARNOCKII N. GEN., N. SP. 339

Velumbrella czarnockii n. sp. 1927. Medusites brzechowiensis Czarnocki, J. Czarnecki, Kambris i jego fauna ..., p. 194 (nomen nudum).1941. Brzechowia brzechowiensis Czarnocki, J. Czarnocki, Kambrium Święty Krzyż im Gebirge (manuscript) (nomen nudum). Holotypus: specimen figured in pl.I, fig. 1 and 2 (part and counterpart).Stratum typicum: Lower Cambrian.Locus typicus: Brzechów, sandstones of the CI f and CI g levels in the Holy Cross Mountains.Derivatio nominis: the species name is given in honor of the eminent specialist on the Holy Cross Mountains, Jan Czarnocki.

Diagnosis. - Jellyfish in the shape of a round disc with diameter up to 80 mm. With probably 28 radial canals, a velum of diameter 28 mm, and a central area 8 mm in diameter.

Material. - 118 imprints, of which none is complete, and only 7 preserve half the disk (pl.I-IV); the others are small fragments. This results not from the state of preservation, but the hardness of the rock (coarse grained quartz sandstones), which does not split at the level of the fossils.These prints are either positive (convex), constituting 42 of the specimens, or negative (concave), comprising the rest of the material. In only two cases (pl. I, fig. 1 and 2) are both parts known. Some discs are flat, others are curved, slightly concave or convex; occasionally half the disc is bent underneath the top, forming a double layer III, fig. 2 On each specimen there are two concentric circular grooves, one smaller and one larger; radial grooves start from the smaller concentric groove. Other ornamentation is preserved only on a few specimens.

Description. - The remains of this jellyfish are layers of rock about half a millimeter thick, in the form of round discs with a diameter ranging from 55 mm to 80 mm. In the central part of the disc, two concentric grooves encircle and define two round areas. The largest area reaches a diameter of 28 mm in most specimens, and the diameter of the smaller area (Fig. l g) barely reaches 8 mm.Concentric striations are seen on the latter (pl. I, fig 1).

28 rays, whose maximum length is around 36 mm, extend from the central area (Fig. 1 cr). All the rays are straight and their spacing is roughly equal, ranging from 6 to 8 mm at the edge of the largest circle, depending on the size of the disc. The rays often extend to the central circle, probably without joining it. The central part is usually destroyed, and the exact path of the terminations of the rays is difficult to observe.

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The larger area is very clearly marked by a deep groove. On certain specimens (Fig. 1 v, pl.I, fig. 1) it forms a ring 5 mm wide. Concentric ridges are visible on this ring (pl. I Traces of short protrusions are visible leaving the outer edge of the ring (Fig. 1 t; pl.I, fig. 1); the largest of which is 10 mm long.

Fig. 1. - Diagrammatic representation of the imprints of Velumbrella czarnockii n. gen., n. sp. cr radial canals, t tentacles, g gastrovascular system central cavity, v velum; natural size. Interpretation of the structure. - I believe that the fossils described above are imprints of Jellyfish. The concentric ridges preserved in places probably correspond to traces of muscle filaments, which among Hydromedusa are more highly developed and concentrated on the edge of the umbrella.

The radial grooves undoubtedly correspond to equally spaced radial canals, and their number is constant, probably 28. These extend from the central cavity of the gastrovascular system, preserved as a small round central area which is concentrically striated. The inner ring likely represents the velum.On one specimen (pl. (pl. I), the inner edge is well defined and the width of the velum can be estimated.

(TRANSLATED) VELUMBRELLA CARNOCKII N. GEN., N. SP. 341

This must have been a heavily muscled membranous ring, as evidenced by concentric grooves reminiscent of the structure of the velum of modern Jellyfish. The outer edge of the velum is preserved as a deep, wide groove. One might therefore suggest that the free edge of the umbrella was equipped with a bead formed by nematoblasts (stinging beads). Short tentacles started from this edge. They are quite clearly visible on one specimen (pl.I, fig. 1). It is surprising that delicate bodies of Jellyfish have left imprints so clear in a coarse grained deposit. These are probably the imprints of the dorsal parts of the umbrella, because the edge of the velum passes through the radial canals. Otherwise, that is to say if at the time of preservation the dorsal part of the medusoid was turned upwards and the ventral part rested on the substrate, the canal passes through the edge of velum. This dorsal position is the same on all the specimens. Such an orientation (dorsal to the substrate) does not seem surprising if one takes into account the lifestyle of some modern Jellyfish in the order Limnomedusae, e.g. the genus Gonionemus (Russell, 1953, p. 401). This jellyfish is common on the east coast of the United States. It lives in the coastal zone, which is unique because this group Jellyfish otherwise all live out at sea. The behaviour of these jellyfish is unique: they rise from the bottom to the surface and when they reach it, they suddenly turn the oral cavity upwards, and in this position they descend to the bottom. They then extend their tentacles as widely as possible and absorb food. Once it reaches the bottom, the animal rests briefly, then reverses itself and begins to rise again.

Judging by the position in which the traces of Velumbrella czarnockii are preserved, it may be possible that this jellyfish had a similar lifestyle, and therefore individuals covered on the subumbrellar side by a sudden influx of sediment remained in the reverse position.

The Jellyfish must have been quite flat, because otherwise they could not, after recovery from the deposit, be flattened such that their imprint is in the form of a regular disk. Also, the velum would have been able to occupy an exactly central position only if the body was very flat.

SYSTEMATIC POSITION

We cannot, on the basis of the material studied, establish more accurate comparisons between the Cambrian Jellyfish of Brzechów and modern forms. Nevertheless, some structural details provide clues as to the assignment of this Medusa to a specific group.

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First, the presence of the velum, which must have been heavily muscled, indicates that Velumbrella belonged to Jellyfish with a velum of the class Hydrozoa. The free edge of the umbrella has left a second deep clear mark. This would indicate the presence of a stinging bead characteristic of Jellyfish belonging to the Order Trachylinida. One can also observe on the Brzechów imprints, other characters of the structure of Jellyfish of this order, e.g. traces of circular muscle filaments, strongly developed among modern Trachylinida.The clear traces of the tentacles also indicate that they must have been fairly stiff, and thus solid, without internal canals. The endoderm filling the axial part of modern Trachylinida forms an axial rod, giving the tentacles greater stiffness, which increases the likelihood of their preservation as fossils. Traces of the gonads are not visible, which may indicate that they were arranged along the radial canals. For example, in the genus Pantachogon Maas, 1893 (Russell, 1953), family Rhopalonematidae, the gonads are arranged along the length of radial canals. Such an arrangement of gonads does not augur well for their preservation as traces on fossil specimens.

Other features, characteristic of the Trachyneminae and observed in the Brzechów jellyfish, include that jellyfish belonging to this sub-family are flat and wider than tall, the mesoglea is not abundant, and the subumbrella and velum are strongly muscled. On the other hand, the number of radial channels is inconsistent with this interpretation, because in recent Trachyneminae there are only eight.

Not only the supposed mode of life of Velumbrella, but probably other aspects may also evoke comparisons to modern Gonionemus. The genus Gonionemus belongs to the order Limnonaedusae created by Kramp (1938). This order includes several genera previously included in Trachymedusae. These two forms are broadly similar. The genus Gonionemus is in the family Olindiidae, representatives of which have more than four or six simple or branched radial canals, and additional converging canals; for example, the genus Olindias also possesses four main canals, and several additional canals that do not extend to the gastro-vascular cavity. We cannot observe the terminations of the radial canals in the genus Velumbrella because the central part is never preserved to allow us to follow the path of the canals in their terminal areas, where they connect to the central area. It seems rather that channels continue right up to the central area, and are unbranched, but this cannot be established with certainty.

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If we look at the Cambrian Jellyfish, judging by the descriptions of the literature available to me, only two genera could be considered similar: Beltanella Sprigg and Ediacaria Sprigg, from the Lower Cambrian of Australia. Both genera have been provisionally incorporated in the order Trachylinida. Beltanella differes by the number of radial canals, of which there are only four, and by the gonads arranged between canals. In contrast, Ediacaria flindersi (Harrington & Moore, 1956, p. 74) seems to have many common features with the genus Velumbrella. Ediacaria probably kept the lower part facing the substrate and therefore the velum could not leave an imprint in the sediment as well as in the case of the genus Velumbrella. The number of radial channels in Ediacaria is also significantly higher. Among the visible canals on the imprints (Harrington & Moore, 1956, p. 74), only a few lead to the central area. On the other hand, the shorter grooves located between them are probably parts of channels which were under the umbrella. Therefore the channels are typically arranged irregularly. In Velumbrella, in general, canals are only partially visible; on the other hand, short grooves, which are probably traces of parts of canals located below the umbrella, are rarely observed. In summary, it seems that Ediacaria could have about 50 radial canals, or a smaller number of main, branched canals. Their total number was thus still greater than in the genus Velumbrella.

Following the comparison with the modern Jellyfish and descriptions of other Cambrian fossil jellyfish, it seems that the genera Velumbrella and Ediacaria could belong to an extinct family of the order Trachymedusae or the closely related order Limnomedusae. Laboratory of Paleozoologyof the Polish Academy of Sciences Warszawa, March 1960

REFERENCES

Czarnocki, J. 1927. Kambr i jego fauna w środkowej części Gór Świętokrzyskich. Komunikat tymczasowy. (The Cambrian and its fauna in the central part of the Holy Cross mountains. Preliminary notice). — Spraw. P. Inst. Geol. (Bull. Serv. Geol. Pol.), 4, 1/2, Warszawa.

- 1941. Kambrium Święty-Krzyż im Gebirge (manuscript). 1-17, Warszawa.Haeckel, E. 1876. Das System der Medusen. Erster Theil einer Monographie der

Medusen. 1-672, Jena.HARRINGTON, HJ & MOORE, RC 1936. Trachylinida. In: Treatise on Invertebrate

Paleontology. 68-76, Lawrence.Kiesling, A. 1924. Fossil Medusae. Fossillum Catalogus. I: Animalia, 1-20,

Neubrandenburg.RUSSELL, FS 1953. The Medusae: of the British Isles. 1-530, Cambridge.

EXPLANATION OF PLATES

Velumbrella czarnockii n. gen., n. sp.

P1. I

Fig. 1.2. Imprints, positive and negative, of one of the best preserved, with traces of the velum and around it, tentacles; × 2 / 3.

Pl II Fig. 1.Two flattened specimens. Deep impressions on the edge of the velum, with traces of tentacles. in the middle of the disc - molding the central cavity; natural size.Fig. 2.Two convex specimens with the edge of the velum clearly marked; × 4 / 5.

Pl III

Fig. 1.A flattened specimen, bearing a wide and deep impression of the edge of the velum; natural sizeFig. 2.A specimen with half the disc folded underneath; × 3 / 5.

PI. IV

Fig. 1-6. Diagrams of the six best preserved examples. The shaded areas correspond to the preserved portions.