SIRENIA. 693 



digits have strong claws or nails. The brain has large olfactory 

 lobes ; the cerebral hemispheres have few convolutions. The 

 tongue is long and protrusible, and the submaxillary glands are 

 large. The stomach is simple. The uterus is simple ; the 

 placenta is discoidal and deciduate. 



Examples. — Dasypus, Chlamydophorus, Tatusia. 

 Glyptodontida3 — extinct Pleistocene types, mostly S. American, 

 but represented in Mexico and Texas. The body was often 

 huge, and was covered by a solid carapace of great strength. 

 ' 6. Manidae — the Ethiopian and Oriental Pangolins, covered dorsally 

 with overlapping horny scales. They are terrestrial, burrowing 

 animals, but sometimes climb trees. They usually feed on 

 termites. Teeth are rudimentary, the tongue is long and pro- 

 trusible. The uterus is bicornuate ; the placenta diffuse and 

 non-deciduate. There is one extant genus, Mam's. 

 7. Orycteropidse — the Ethiopian Aard-varks, represented by two 

 species of Orycteropus, ranging from S. Africa to Egypt. They 

 are shy, nocturnal animals, living in burrows, feeding on termites. 

 There are numerous complex teeth, differing in structure from 

 those of any other known Mammal. The skin bears scanty 

 bristles. The mouth is tubular, and the tongue is narrow and pro- 

 trusible. The digits bear nails suited for digging. Tfife uterus is 

 bicornuate, the placenta broadly zonary. The relation to the 

 other Edentates, or, indeed, to other Mammals, is uncertain. 



Order Sirenia. Sea-Cows. 



A small decadent order of sluggish, aquatic, vegetarian 

 Mammals, in no direct way connected with Cetaceans, to which 

 they have some superficial resemblance (convergence). There 

 are two living genera, — Halicore (Dugong) and Manatus 

 (Manatee), and one was recently exterminated (Rhytina). 



The Sirenia are sluggish, with massive heavy bones, a 

 plump body, some oil, and sparse hair on the thick tough 

 skin. In adaptation to aquatic life, they have a fish-like 

 form, a powerful tail with a " caudal fin," no external trace 

 of hind-limbs, flipper-like fore-limbs, no external ear, valved 

 nostrils at the end of the snout, networks (retia mirabilia) 

 in the arteries (useful in prolonged immersion). They are 

 herbivorous, feeding on algae and estuarine plants ; and, 

 like others of similar habit, have a chambered stomach, a 

 long intestine, and a caecum. 



They are primitive, and with this fact may be associated 

 the abdominal testes, the absence of distinct epiphyses on 

 the vertebrae (cf. Prototheria), and the small brain with few 

 convolutions. 



