OCR Text |
Show 1882.] PROF. W. H. FLOWER ON THE EDENTATA. 363 eaters are closely similar in structure, while those of Manis are upon a totally different type. In the former families the testes are placed exactly in the same situation, close to each other, lying on the rectum, between it and the bladder; the penis is quite rudimentary, consisting of a pair of small corpora cavernosa, not directly attached by their crura to the rami of the ischium, and having a glans scarcely larger than that of the clitoris of most mammals, and, as in birds and reptiles, without any true corpus spongiosum. The number and development of the accessory glands vary apparently in different species of both families. In the females of both Anteaters and Sloths the uterus is simple and globular, and the vagina, at least in the virgin state, is divided into two channels by a strong median partition. Lastly, the placen-tation, as far as it is known, if not identical, is similar in principle. The placenta of Choloepus has been fully described by Turner; it is deciduate, and composed of a number of lobes aggregated into a dome-like mass. There is nothing in the descriptions, certainly less complete, of the placenta of Tamandua and Cycloturus to show any differences except in detail of form. In Manis, on the other hand, the testes are totally different in position, lying in the inguinal canal. The penis is external and well developed. The uterus is truly bicornuate, the vagina not divided, and the placenta diffused and non-deciduate. All tbe organs and fcetal membranes are formed very much on the plan of those of the typical Ungulata, without a trace of the special peculiarities of the American Edentates. As regards the tegumentary system Myrmecophaga closely resembles Bradypus in the character of its hairy covering; while Manis, in its very remarkable horny scales, shows a type entirely different from both and from every other mammal. Many other minor considerations might be adduced ; but I think I have brought forward enough to establish the fact beyond reasonable question, that Manis, if allied at all to Myrmecophaga, must have separated from the original common stock before this had given off the Bradypodida-or, in other words, that the Sloths and Anteaters, with the Megatherioids intervening, are far more nearly allied to each other than either is to the Pangolins. It now remains to examine the position of the other families. Dasypodida. In many respects this family is remarkably specialized, more particularly in the characters of the integumentary structures, in which it differs from all known mammals. In dental characters it presents nothing fundamentally different from those of the Sloths. In lingual, salivary, and digestive organs, on the other hand, it is more nearly allied to the Anteaters, though presenting a less extreme form of modification, showing in fact one of the stages by which such modification may have been brought about. It is therefore so far a connecting link between these families. In the extremely important character of the presence of interlocking accessory zygapophyses to the lumbar vertebrae, and in the structure of the sternum and sternal ribs, it follows the type of Myr- |