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Show 1873.] MR. ST. G. MIVART ON THE LEMURS. 485 8. The transverse diameter of the thorax exceeds its depth. 9. The dorsal region of the spinal column is relatively very short. 10. The cartilages of the ribs slightly expand before joining the sternum. 11. There are no hyperapophyses. 12. There is no intermedium in the carpus. I find, on the contrary, that it differs from J. brevicaudatus in that the groove which extends along the axillary margin of the scapula is not visible on the dorsum of that bone, as also that the anterior inferior spinous process of the ilium is relatively smaller and less prominent. There are, moreover, one or two caudal chevron bones ; but these are minute. The absolute and relative dimensions of the bones are given in the Table annexed to this paper. The skull and skeleton of J. diadema* are those of a specimen which, from the condition of the teeth, is evidently even more than adult. Comparing it with the description and figure of the immature specimen from Berlin before described by mef, I find that, with slight differences as to proportion and development of ridges, due to age, it agrees completely, except that there is a minute malar foramen, that the posterior palatine foramen situated behind the last molar cannot be called small, and that the canines are long and pointed and destitute of that production of the anterior margin which exists slightly in Indris brevicaudatus and so largely in I. laniger. The size and proportions of the skull are extremely like those of I. brevicaudatus; but in the adult, as in the young, the muzzle is slightly shorter relatively. The axial and appendicular skeletons show also a great resemblance to the same parts in I. brevicaudatus, except that the humerus is relatively longer, and the femur shorter, while the ulna is stouter and diverges further from the radius. The scapula and ilium agree with those of I. brevicaudatus in that the former has the axillary groove visible on the dorsum of the bone, and the latter has an anterior inferior spinous process greatly developed; it is even more developed than in /. brevicaudatus. As regards the twelve points above enumerated (as those in which JT. laniger agrees with I. brevicaudatus and differs from the genus Lemur), I find that I. diadema agrees with the other Indrisinee examined by me, except that the spine of the axis extends somewhat backwards over the third cervical vertebra. I find no chevron bones attached to the caudal vertebrae; but they may have been accidentally lost, as has no doubt been the case with the intermedium of the carpus, since Professor Alphonse Milne-Edwards has been so kind as to inform me that this bone exists in all the individuals (about * No. 15336; 70. 5. 5. 2 in the British-Museum collection. t P.Z.S. 1807, p. 247, pl. xviii. |
