Abstract
THE ANATOMY AND AFFINITIES OF THE AYE-AYE.—Dr. Alix having recently dissected a young male Aye-aye (Chiromys Madagascariensis), communicates, through Prof. Gervais, to the Academy of Sciences of Paris (Comptes Rendus, July 29, p. 219), some notes on certain. points in its anatomy which bear upon the much-vexed question of the position of this curious animal in the mammalian series. It seems that his observations confirm in all points the opinion of all those eminent naturalists who, in accordance with De Blainville, and contrary to Gmelin and Cuvier, have held that the Aye-aye must be approximated to the lemurs and separated from the rodents, fresh facts being brought forward in support of this view. First, as regards its myology. The extensor communis hallucis, which in rodents is attached to the outer condyle of the femur, arises in the Aye-aye from the tibia. The biceps brachialis, which has only one head in the majority of rodents, has two in the Aye-aye. The supinator longus, which is generally absent in the rodents, has in the Aye-aye a good development. The common extensor of the digits, to those of the hand or foot, is composed of two distinct fascicles, of which one furnishes the tendons of the second and third digits, the other those of the fourth and fifth, from which it results that the Aye-aye, like the other Lemurina, possesses a paired digital system, and resembles in this feature the cloven-hoofed Pachyderms and the Ruminants, while the other mammals have, under all relations, an unpaired digital system. Dr. Alix has, moreover, verified the presence of a rotator muscle of the fibula, previously mentioned by Dr, Murie and Mr. Mivart in their paper upon the anatomy of the Aye-aye, published in the Proceedings of the Zoological Society. In examining the nervous system of the cervical region arrangements were discovered quite different from those seen in rodents. For example, the trunk of the great sympathetic nerve, which is otherwise separated from the pneumogastric in the whole extent of this region, has no middle cervical ganglion, but only an inferior one, excessively reduced in bulk. The superior cervical ganglion, situated immediately above the bifurcation of the common carotid, adheres by its fibrous sheath to the pneumogastric; and it is at this spot that the superior laryngeal nerve detaches itself from the pneumogastric, crossing the ganglion with which it enters into connection. On the left side there is no indication of a nervous filament answering to a depressor nerve, while on the right there may be seen to detach themselves from the superior laryngeal nerve two filaments of excessive tenuity which go to rejoin the trunk of the great sympathetic nerve. Nothing in this arrangement suggests resemblance to the nervous cord so distinct among the rodents, and above all among the Leporidæ, which, from this very circumstance, have furnished physiologists with the opportunity of making experiments of the greatest value. This character distinguishes the Aye-aye also from the opossums, which were placed by Illiger with the apes and lemurs in his order
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G., J. BIOLOGICAL NOTES . Nature 18, 645–646 (1878). https://doi.org/10.1038/018645a0
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DOI: https://doi.org/10.1038/018645a0