552 Mr. Martin A. C. Hinton on

of which is deeply emarginate, the notch wider thar~ either lateral lobe. Basistyle, b, unusually short and stout. Inner dististyle, id, with the portion beyond the basal fracture very short ; outer style long, glabrous.

Hab. Peru (Junin). Holotype, ~, Tulumayo Valley, Tarma, altitude 4000-

8000 ft., November 8, 1940 (Woytlcowslci). Gnophomyia (Gnophomyia) lonqitergata is readily told

from other simiL-or black sl)~cics of the subgenus that have uniformly blackened antennae, halteres and legs, by the large size and by details of structure of the male hypopygium, especially the long-produced, emarginate median lobe of the tergite.

XLVIII.--Preliminary Diagnoses of five new Murine Rodents. from New Guinea. By MARTIN A. C. HrSTON, F.R.S. (From the Department of Zoology, British Museum (Natural History).)

AN important collection of mammals from New Guinea has been received from that most careful collector, Mr. F. Shaw Mayer. A full account of this collection will be published later on elsewhere ; but in the meantime it seems advisable to publish the following diagnoses. I t is not possible in present conditions to proceed with the registration of the collection ; but the types are all deposited in the Museum and they are specified below by references to the collector's original numbers.

BAIYANKAMYS. gen. nov. (Hydromyinse.) Genotype: Baiyanlcamys shawmayeri, sp. n. A small Hydromyine Rat, modified for aquatic life,

with ] cheek-teeth, and with proportionately shorter palate than in allied genera. The dental formula appears to be unique in the whole family Muridse.

Baiyankamys shawmeyeri, sp. n. Type-locality: Baiyanka, Purari-Ramu Divide, South-

East Bismarck Range, North-East New Guinea. Altitude 6500 ft. Type No. 713. Male, collected

June, 1940, by Mr. F. Shaw Mayer. " Caught by a s t r eam

five new Murine Radents from New Guinea. 553

in the open grass country. Muzzle enlarged but not so much as in Parahydromys asper."

General skull characters not unlike those of Para- hydromys and Hydromys chrysogaster, but size considerably smaller than either. The frontals proportionately wider than in H. chrysogaster but narrower than those of Parahydromys. Palate shorter, about haft occipito-nasal length (considerably more than half occipito-nasal length in the two allied genera). Tooth-row proportionately shorter than in the two allied genera. Molars much narrower, the width of M 1 is 1-7 mm. (In Parahydromys, t h e width of M 1 is over 3 ram., and in H. chrysogaster esox it is 2"9 mm.) Brain-case wide, but less so than in Crossomys, from which the new form further differs in its normal functional ear. Nasals receded anteriorly. Zygo- matic plate normal for the group. The teeth, which are somewhat worn, are much like those of Parahydromys, but in the lower jaw there is a narrow elongate M3, which is probably functional. This tooth is about as long as .M 2 and apparently has one re-entrant fold each side, with quite a well-marked narrow posterior heel. (On the left side of the mandible, M3 has fallen out, and spaces for two roots may be observed.)

The size of the new form is nearest Hydromys habbema Tare, Amer. Mus. Nov. 1101, 1941, p. 3. ([ can find no mention of dental characters in detail in Tate's description, and assume that H. habbema has the cheek-teeth ~ as is normal for Hydromys.) The new form also appears to differ from H. habbema in its larger ear, shorter palatal length, and shorter foramina, as well as the presence of the third lower molar.

The fur is very thick; dark grey above, paler grey below. Tail is well haired, wholly dark basally, the terminal quarter white. Feet large, the middle digits slightly webbed. Hands very small, as is usual in Australasian Water-Rats.

Measurements (in millimetres) : - External : Head and body, 146 ; tail, 176 ; hind-foot,

36.5 ; ear, 13. Skull: Occipito-nasal length, circa 32.5; condylo-

basal length, 32.8 ; front of incisors to back of palate, 16.3 ; diastema, 8.4 ; palatal foramina, 3-5 ; bulla, length, 4.0; upper tooth-row, 4.7; nasal length, circa

Ann. & May. N. Hist. Set. 11. Vol. x. 39

554 Mr. Martin A. C. Hinton on

10.5 ; least interorbital width, 5-2 ; width of brain-case, 14.7 ; width of M 1, 1.7.

Melomys fellowsi, sp. n.

Type-locality: Baiyanka, Purari-Ramu Divide, South- East Bismarck Range, North-East New Guinea.

Altitude 8000ft. Type No. 695. Male, collected June~ 1940, by Mr. F. Shaw Mayer. Eight specimens.

A Melomys with a strongly elongated tail (averaging 136 per cent. of head and body) ; incisors white in colour ; proportionately short palatal length; zygomata very little spread out from sides of skull, and rostrum rather heavy.

Skull in general reminiscent of Melomys levipes, but hind-foot somewhat broadened and of arboreal type, and tail much more elongated than in levipes; more as in M. fulgens. Palatal foramina short (about 14 per cent. of occipito-nasal length), not reaching the tooth-rows. Bull~e rather large for a member of this genus.

Mamm~e 0- -2=4 , in four specimens. Tail with about ten rings to 10 mm. Back brown, belly dull yellowish brown.

This species seems to combine the skull of the levipes group with the external characters of the arboreal long- tailed fulgens type, and in addition its white incisors appear to be a most unusual character in this genus.

Measurements of type (in millimetres) : - External : Head and body, 141 ; tail, 190 ; hind-foot,

29.5 ; ear, 19.5. Skull: Occipito-nasal length, 35-0 ; condylo-basal length,

31.1 ; front of incisors to back of palate, 15.8 ; diastema, 8.3 ; palatal foramina, 5.1 ; bulla, length, 4.6 ; upper tooth-row, 6.1 ; nasal length, 12-5 ; least interorbital width, 5.9; zygomatic width, circa 15-4; width of ~ /1 , I'9.

In the series, the occipito-nasal length varies between 34.5 and 36"2 ram. ; and the head and body varies between 139 and 150 ram. Hind-foot 31 mm. at most.

Pogonomelomys tatei, sp. n.

Type-locality: Baiyanka, Purari-Ramu Divide, South- East Bismarck Range, North-East New Guinea.

five new Murine Rodents from New Guinea. 555

Altitude 8000 ft. Type No. 708. Female, collected June, 1940, by Mr. F. Shaw Mayer. "Mamm~e 0--2 ~4. Dorsal surface tail-end bare (prehensile)."

Tare, Amer. Mus. Nov. 1101, 1941, p. 5, has drawn attention to the fact tha t in certain species hitherto referred to Melomys, the tail has the dorsal surface at its termination bare and prehensile, and has given generic rank to these species under Riimmler's name Pogono- melomys (1936, Zeitschr. f. S£ugetierk, xl. p. 252). I-Ie ~tates that M. bruijnii, M. mayeri, and M. rttmmleri have this specialization present. In the present collection there are three specimens of an apparently new species which also has this character as noted by the collector.

They are apparently like P. rammleri Tate, 1941, Amer. Mus. Nov. 1101, p. 6, but considerably larger in most of their dimensions. Tate gives the measure- ments of ri;~mmleri as : total length 242 ram., tail 138 mm., ear 17 mm., and condylo-incisive length 26.1 mm. These new specimens have the total length not under 306 mm., the tail not under 174 mm., the ear not under 18-5 mm. and the condylo-incisive length not under 30-4 mm.

Both ri~mmleri and the new form have long palatal foramina (in the new form averaging 17 per cent. of oecipito-nasal length), and thereby they differ from mayeri and apparently bruijnii, which have proportionately shortened palatal foramina.

The new form further differs cranially from P. mayeri in its narrower frontMs, and rather larger bullm.

The tail is elongated, averaging 136 per cent. of head and body, and with roughly twelve rings to 10 mm. Back light brown, belly grey.

Measurements of type (in millimetres) : - External : Head and body, 133 ; tail, 185 ; hind-foot,

25 ; ear, 19. Slcull: Occipito-nasal length, 35.1; condylo-basal, 31-8;

front of incisors to back of palate, 16.1 ; diastema, 8.6 ; palatal foramina, 5.8 ; bulla, length, 4.6 ; upper tooth-row, 6.0 ; nasal length, 11.2 ; least interorbital width, 4.8 ; zygomatic width, 17-8 ; width~of M 1, 1.7.

In the three specimens, the occipito-nasal length varies between 33.7 and 35.1 mm., the palatal foramina between 5.6 and 6.2 mm., the head and body 132-134 mm.

39*

556 Mr. Martin A. C. Hinton on

Rattus shawmayeri, sp. n.

Type-locality.--Baiyanka, Purari-Ramu Divide, South- East Bismarck Range, North-East New Guinea.

Altitude 8,000 ft. Type No. 636. Female, collected May, 1940, by Mr. F. Shaw Mayer.

A single specimen, collected at the above locality, represents evidently a species of Rattus totally unrelated to any hitherto described from New Guinea, and super- ficially most like Rattus ehtt of the eastern H~malayas.

I t is characterized by very small size f5~ the genus (head and body 97 ram., occipito-nasal length 27.9 mm.), strongly elongated tail (163 per cent. of head and body), small bullm, very weak supraorbital ridges, palatal length less than half occipito-nasal length, but palatal foramina long. All these characters are paralleled to a greater or lesser degree by Rattus eha, from which the new form differs in its smaller occipito-nasal length, considerably narrower frontals, and proportionately shorter tooth-row.

The lower incisor root of the new species forms a noticeable knob on the outer side of the jaw, just behind the coronoid process. Molars without special peculiarity ; M 3 is less reduced than in Rattus eha. The frontals are strongly constricted, and the brain-ease is broad.

Rattus exulans, which is another species sometimes as small as this new form, belongs to a different group of the genus, and has much larger bull~e, longer palate, and quite strong supraorbital ridges.

The tail is mostly dark in colour, but the terminal 25 mm. is pale. There is a certain growth of hair through- out its length, and the tail is different in this character from Melomys.

The fur is soft ; back dark brown, belly whitish grey. Fifth hind-toe relatively long. Approximately fourteen rings to 10 mm. on the tail.

Measurements of the type (in minimetres) : - External: Head and body, 97; tail, 159; hind-foot,

23.5 ; ear, 16. Skull : Occipito-nasal length, 27.9 ; condylo-basal length,

25-2 ; front of incisors to back of palate, 13.2 ; diastema, 6.6; palatal foramina, 4.7; bulla, length, 3-7; upper

five new Murine Rodents from New Guinea. 557

tooth-row, 4-1 ; nasal length, 9.5 ; least interorbital width, 3.8 ; width of brain-case, 12.3 ; width of M 1, 1.3.

Rattus rosalind, a, sp. n.

Type-locality.---Tapu, Upper R a m u River Pla teau, Nor th-Eas t New Guinea.

Alti t i tude, 6,000 ft. Type No. 588. ~emale, collected April, 1940, b y Mr. F. Shaw Mayer. (" Mamm~e 2- -2 = 8 "). Eight specimens.

Very similar to Rattus leucopus, but so much smaller than the smallest race of tha t species tha t it seems to warrant specific recognition.

Rtimmler gives the measurements for R. leucopus (in Mitt. Zool. Mus. Berlin, 1938, xxiii. 1, p. 179), as head and body length, 170-275 mm. ; hind-foot, 33-49 mm. ; condylo-basal length, 3 8 . 2 - 5 3 . 6 m m . ; molar length, 6.7-8.6 mm.

The same for R. rosalinda is : head and b o d y length 127-149 mm. ; hind-foot, 25-29 mm. ; condylo-basal length, 32.1-35.3 mm. ; molar length, 6.0-6"6 mm.

Distinguished from R. exu/ans, which sometimes m a y be as large cranially as this new form, and with which it occurs, b y its much wider molars and proport ionately smaller bull~e, and longer palate. The width of M 1 is not under 2 ram.

The tail is shorter than head and body, as in R. leucopus (averages 83 per cent. of head and body in the sel~ies), and is dark in colour, and quite well haired. Back dark brown, belly dark grey.

Measurements of type (in miUimetres) : - External: Head and body, 131; tail, 116; hind-foot,

28 ; ear, 18. Skull : Occipito-nasal length, 35-1 ; condylo-basal length,

34.4 ; front of incisors to back of palate, 19.3 ; diastema, 10.0 ; palatal foramina, 6-4 ; bulla, length, 5.4 ; upper tooth-row, 6.4; nasal length, 11.9; least interorbital width, 5.8 ; width of brain-case, 13-5 ; width of M 1, 2" 1.