364 PROF. W. H. FLOWER ON THE EDENTATA. [Apr. 18, 



mecophaga and Megatherium ; but in the peculiar form and ankylosis 

 of some of the cervical vertebrae, common to all existing members of 

 the family, it stands apart from all other Edentates. In the presence 

 of a clavicle it resembles the other American forms ; but it differs in the 

 shape of the scapula, and in the existence of a third trochanter to the 

 femur. The structure of the extremities, especially the manus, presents 

 many modifications, some of which are quite comparable to, though not 

 identical with, those of the Myrmecophagidce. 



The reproductive organs differ in the presence of a largely de- 

 veloped copulating organ in the male, and of a simple vagina of cor- 

 responding length in the female ; these, as long ago suggested by 

 Professor Owen, appear to be correlated with the difficulties which 

 would otherwise be interposed to sexual congress by the arrange- 

 ments of the dermal armour, and which of course do not occur in 

 the Sloths and Anteaters. The testes are still abdominal, though 

 not in the same position ; and the penis, notwithstanding its size, 

 wants (as pointed out by Morrison Watson ') both the glans and 

 bulb, generally formed in mammals by the corpus spongiosum. The 

 uterus is as simple, or nearly so, as that of the Sloths »nd Anteaters ; 

 and there is no reason to supjiose, from what is at present known, that 

 the placentation differs in principle from that of those families ; for if 

 deciduate, whether the whole mass assumes an oval, discoidal, or 

 bell-shaped form is only a matter of detail. 



The Armadillos, then, have undoubtedly near affinities to the 

 other American Edentates, and are probably members of the same 

 group, though not so nearly related to either of the other families 

 as they are to each other, and are moreover remarkably specialized 

 in a particular direction. The Glyptodonts form an allied group, 

 agreeing in most essential features, but also presenting some very 

 singular special modifications. 



Lastly, Orycteropus is a form in most respects perfectly apart 

 from all the others. The structure of its teeth alone would almost 

 entitle it to be placed in an order by itself, were it not for the 

 practical inconvenience of doing so. Its vertebral column is formed 

 on the normal type of mammals. Its limbs also present com- 

 paratively few specializations ; but it resembles the Armadillos in pos- 

 sessing a third trochanter to the femur. Its digestive organs are 

 also comparable to those of the Armadillos, as its mode of feeding 

 is similar. But its reproductive organs, both male and female, and 

 placentation are formed upon a principle unknown in other Eden- 

 tates, or, in combination, in other mammals. The testes, in a specimen 

 I once examined, were inguinal, though they appear to descend, at all 

 events temporarily, into a scrotum ; but the penis is almost as small 

 as in the Great Anteater. The uterus is more bicornuate than in 

 Manis, the two lateral chambers opening separately into the vagina, 

 as in some Rodents. The placenta, as described by Prof. Turner, 

 is broadly zonular ; but whether deciduate or not is at present un- 

 determined, probably the latter. As Balfour remarks, this type of 

 placenta is capable of being easily derived from that of Munis, 



» P. Z. S. 1878, p. 677. 



