OCR Text |
Show 874 MR. OLDPIELD THOMAS ON A NEW [Dec. 17, Diprotodonts, its length in front of the jaw-bone exceeding that of the three anterior molars. Succeeding it, just as in the same Australian group, are four minute unicuspid teeth, which it seems best tor the present tentatively to call two premolars, one canine and a premolar. Any other determination would involve the presence of tour incisors or four premolars, each equally unlikely. Then come two narrow, pointed, two-rooted teeth, obviously premolars, the posterior slightly longer than the anterior, and, as in the upper iaw, pst overtopping the molars. Molars low-crowned, more or less oval m section, and each with two roots. Their pattern is difficult to make out accurately, owing to a doubt as to h o w far they are affected by wear. The anterior ones each seem to have two curved or angular crests, whose concavity is directed inwards, somewhat similar to those of the Indian Ehinoceros, but they are far less distinct; the posterior is larger and more open as compared with the much smaller and less open anterior one, and they are very probably produced in a wholly different way ; the anterior crest is decidedly higher than the posterior. The last molar is much smaller than the other, and has two pointed cusps corresponding to the crests of the other teeth : both rather inwards of the middle line. The following are some dimensions of the specimen described the type of C. obscurus : - Head and body 151 mm.; tail 144; hind foot without claws 23 • heel to end of hallux 14*2 ; hallux 3*2 ; ear 12 x 11*5. Skull-basal length 33*6 ; greatest length in middle line 36 • greatest breadth 18; nasals, length 17*8, greatest breadth, approximately, 5*4; intertemporal breadth 7; breadth of brain-case 12*8 ; height of brain-case above basilar suture 9 ; palate, length from gnathion 20*6, breadth outside m 2 8*3, inside m* 5; anterior palatine foramina 6'2; length of palatal vacuities 7*2; combined length of m s > 3 5-1. Lower jaw, length from condyle, bone only 23*8, including ii 28*5; height of coronoid above angle 10; vertical thickness of ramus below m1 3; length of i" beyond bone above 6 ; length of lower molar series 6*9. We may now pass from these necessary, but dry and uninteresting details to the important question as to what Marsupial Ceenolestes is most nearly allied to, for Marsupial it is in every character. With regard to living members of the order, the answer can only be that it is allied, at least closely, to none, but that, so far as it has any existing relations, these are distinctly the Australian rather than the American Marsupials. For it is clearly a Diprotodont, as not only does it possess the characteristic development of the lower incisors, but even tbe molars resemble most closely in structure those of certain members of the family Phalangeridee, while being wholly unlike those of the typical Polyprotodonts. * From all of the existing Diprotodonts, however, apart from its habitat and numerous detailed differences, Ceenolestes is at once distinguished by its not being syndactylous, a character which is |