NOTICC oj' Fos+ CRUWACIU, Jrcim R&Jetjey. By hit. VAN RENSSELAEB, M. b. Read f i o ~ . i5, .182&

NEW-.?ERSEY presents t& us the richest ldcditikd afg ibss& with which we are acquaitlted in this hemisphere. Situiitkb between the two great schools .of natural history, it is sut'pkh- h g that it has never' been made the scene of more extensive research. T h e cursory 'examinations it hqs 'teceived fiom both cities have proved SO gratifying, that we ma'y hope sohie leisared brother will be itldlrced to itivestigate mbte triihutely the depository bf these medats of nature, so abundant in our tertiary region," and more particularly in the triangular peninsula comprised between the ocean and the Delaware and Raritan rivers.

Ddring an excursion made to this interesting region, dome months ago, in cornpang aith Megsrs. Dekay and Cooper, we had the satisfaction of incfeasing the cabinet of the Lyceum by the addition of the fossil remailis of the .Mastodon.+ I have now the pleasure of noticing some specimens of fos- sil crustacea found during that excursion, aod. which are the first of the kind found in this country, 80 far as my know ledge extends : certainly tbe first tbat have been descri&d. There are portions of a crab in the cabinet of the Academv of Naturai Sciences at Philadelphia, said to have been found below the surface of the soil on the banks of the Potothac : but 1 am informed they bear no other evidence of*being fmsil,#

* Whkb I bave partjal?y described in a paper iead before the New-York Liter* and Pbilosopbicd Society iP March lbt, and which bas beenor- &red to appear in the next valnme of their Transactions.

t Vide page 143 of tbiS volume, Immediately after this paper was read, Major Delahld informed me

tbat he had prrt df a fossil m b from York river; but he brri hevdr been able to bnd it since.

tt is mucb to be regretted that no ecientih wwk has pointed out tho'&, tinctire charactera of fossil and merely preserved shcb.

196 On Fossil Ctustacea from New-Jersey.

The,remains in our cabinet consist of fragments only': that is to say, we have parts of eight hands, mqre or less perfect, (four of the right side, three of the left, and one doubtful,) and the third joint of one of the legs. The great dissimilarity of these severs\ parts eviuces to me four very distinct vatie- ties, which I shall endeavour to describe, in reference to Plate XIV. 5 ,

Fig. 1. The right hand of a crab viewed internally, where it is flat and smooth ; externally, 'protuberant. The finger moveable. Thumb and finger of equal length, smooth, slightly compressed internally, and rounded externally. We have the corresponding left hand in a more perfect state as to outliiie, but with small parts of tbe finger wanting.

Fig. 2. This specim'en is unfortunately much fractured. I have presented an external view of the left hand, which has suffered great violence, and has the finger and thunrb bro- ken and out of place, but still slightly adhering. The lower margin of the hand is smooth, as is the outer margin of the finger; the thumb, on the contrary, has a double row of small spines accompanying its lower margin.

Fig. 3. Represents the 'interior of another left hand, on which . * only small parts of the thumb and finger are visible. The exterior is beautifully circular, the interior ovate and emarginate. In the central line are several small spines or tubercles, which are again observed .more thickly surround- ing the root of the thumb, and extending along its upper margin. Part of this-thumb has been accidentally broken off since we found it. We possess also a right hand, about as perfect as this, which, from its position when found, and the&\rong resemblance, I take to be its fellow; it certainly belonged to a s animal of the same species.

Part of a claw, with the greater part of the thumb and finger. The claw is compressed and emarginate. The smaller finger is an irregular triangle, bearing spines

+ *' Fig. 4.

on the angles. The thumb or ‘longer finger hao five rows of spines .extending its whole length, and approrimicing towards the smaller extremity.

It is exceedingly difficult to trace analogies between fossil end recent species, eFpec’lally where oirly .parts of‘, the animals are offered for observation. Moreover, the old Linnean geiius Cancer has undergone so many alterations aid modifications I

by the labours and observations of Fabricius, Box, Latreille, and Leach, that it is riot easy to arrange recent, much less fossil specimens. fig. 4. presents many points of resemblance with the Pagurur Faujasii of Desmarest, as exhibited in PI. XI. fig. 2. of his work on Crustacea, in conjunction with M. Brongniart on Trilobites. It strongly resembles the smaller claw on that plate, the original of which was from. Maestricht, and describ- ed by Faujas St. Fond as the Pagurc Z ’ A m i t c : and which Latreille notices as approximating very nearly to the Pagutub Bernhardus. The analogy between the recent and fossil is so great, that they might easily be mistaken : the only diffeience, perhaps, being the length of the claw. A circumstance * tehd- iog to confirm, the supposition of M. Latreille, that it was the hermit crab, is the fact that only claws are found at Maestricht., and never the body, which he accounts for naturally from the durability. of the claw, aud the liability of the body to,de- composition. Although at Tinton Falls we saw many claws,. neither of us could discover any.other part of the animal.

Messrs. Cuvier and Latreille place all the fossil crustacea hitherto found (with the exception of two specitpens) in the first order, viz. decapode : .so that we are probably correct in the place assigned to our new varieties of fossil.

The crabs of Maestricht are found in a formation analagoue * to, perhaps equivalent witb, the.chalk ‘of ‘Englaod, in which

Mantell first noticed them. They are found in the plastic

. I must be allowed to remark, however; that .

I

198 On Fossil Cruatacea from New- JerJcy.

clay of the isle of Sheppey-in the calcaire grossier of Paris- in the limestone of.Pappenheim-and iri the tertiary of New- Jersey ; the precise spot seems to be a conglomerate sand strongly tinged with iron.

It has been remarked- by Desmarest, that io geological po- sition the trilobite is older than the crustacea-but with no great diffetence’of age.; and that tbe trilobites end, where the crustacea begin : a remark that- will probably be tontirmed by the &lathe position of our OWD trilobites and crustaceii, if indeed they are to be considered separately.

A SKETCH of the GEOLOGY of the ISLAND OF MONTREAL. By J. J. BIGSBY, M. D. Read Dec. 13, 1824.

Tax picturesque and fertile island of Montreal, having close oil its north the smaller “ Isle Jesus,” is situated seventy- six miles above tidewater, in the Stk Lawrence, at tbe con- fluence of that river witb the Ottawa. It is chiefly embraced by the waters of the latter stream ; on the north by its small fork, called the ‘‘ Rivihe des Prairies,” dowing through low grounds, and occasionally checked by ledges of limestone ; on the west, by its large and irregular expansion; the Lake of the Two Mountains; on the south by Lake St. Louis,” (in which the two rivers join without mingling) and the rapids forming.its outlet, w&cb turu round the great soutb angle of theisland, and pnss, with intervals of tranquillity, for eleven miles over reefs and stony shallows ; finally, it is contained

* Ita Icngth passes n e d y east apd west, and is eighteen miles, by eight miles in Gatest bkdth. The purplish brown water of the 0th- occu- piis’the half nearest M o n W Sslad, the line of separation beiog abrupt aud pretty etkiight.