ORYCTEROPODIDM 209 



in the centre, from which the dentinal tubes radiate outwards, and 

 being closely packed together each system assumes a polygonal 

 outline as seen in transverse section. The small anterior teeth have 

 milk-predecessors which are fully noticed below. Skull moderately 

 elongated. The facial portion subcylindrical and slightly tapering. 

 The zygoma complete and slender. The palate ends posteriorly in 

 the thickened transverse border of the palatines, and is not 

 continued back by the pterygoids. The tympanic is annular, and 

 not ankylosed to the surrounding -bones. The mandible is slender 

 anteriorly, but rises high posteriorly, with a slender recurved 

 coronoid, and an ascending pointed process on the hinder edge 

 below the condyle, which is small, oval, and looks as much forwards 

 as upwards. Vertebrae: C 7, D 13, L 8, S6, 027. The large 

 number of lumbar vertebrae is peculiar among Edentates. Tongue 

 less vermiform than in Myrmecophaga, being thick and fleshy at the 

 base, and gradually tapering to the apex. The salivary apparatus 

 is developed much in the same manner as in that genus, but the 

 duct of the submaxillary gland has no reservoir. The stomach 

 consists of a large subglobular cardiac portion, with a very thick, 

 soft, and corrugated lining membrane, and a smaller muscular, 

 pyloric part, with a comparatively thin and smooth lining. There 

 is a very distinct ileo-csecal valve, and a considerable-sized csecum ; 

 also a gall-bladder. Head elongated, with a tubular snout, terminal 

 nostrils, and small mouth-opening. Ears large, pointed, erect. 

 Tail nearly as long as the body, cylindrical, very thick at the base, 

 tapering to the extremity. 



The reproductive organs and placentation of Oryderopus are 

 formed upon a principle unknown in the more typical Edentates, 

 or, in combination, in any other mammals. Thus the testes, in the 

 one described example, were inguinal, but appeared to descend, at 

 all events temporarily, into a scrotum ; but the penis is scarcely 

 larger than that of the Great Anteater. The uterus is still more 

 fully bicornuate than in Manis, with its two lateral chambers 

 opening separately into the vagina, as in certain Rodents. The 

 placenta is broadly zonary, but it is not known whether it is 

 deciduate or not. It might readily be derived from the diffused 

 placenta of Manis by the abortion of the foetal villi at the two poles 

 of the ovum. 



The Orycteropodidce have long been regarded as widely different 



from other Edentates, their presumed affinity with the Manidce 



being more or less problematical ; but the discovery recently made 



by Mr. 0. Thomas l that they have a milk-dentition still further 



emphasises their aberrant nature. According to this observer, it 



appears that there are normally no less than seven milk-teeth in the 



upper jaw, the hindmost of which is far larger than the others, 



1 Proceedings of the Royal Society, vol. xlvii. p. 246 (1890). 



14 



