300 



MAMMALIA 



I. APLACENTALIA. 



Order 1. MONOTREMATA.* 



The jaws are elongated to the form of a leak; the feet are short, five- 

 toed, and furnished with strong clatvs. Marsupial bones and a cloaca 

 are present [Oviparous ;t with meroblastic ovum.'] 



The most important character of the Monotremes is the presence 

 of a cloaca. The dilated end of the rectum receives the openings of 

 the generative and urinary ducts (fig. 678 a). In addition to this 

 character we must mention the simple condition of the female 

 generative organs, the absence of teeth in the jaws, the possession 

 of a large coracoid, and the slight development of the corpus 

 callosum. 



FIG. 632. Or nithorJiyn chits parudoxut. 



The form of the body and the mode of life of the Monotremes 

 partly recall the Anteaters and Hedgehog (Echidna hystrix,&g.6Sl) 

 and partly the Otters and Moles (Ornithorhynchus) ; in fact, Or-, 

 nithorhynchus received the appropriate name of " Watermole " from 

 the Australian settlers (fig. 682). Echidna is covered with strong 

 spines, and possesses an elongated edentulous snout, with a vermi- 

 form, protrusible tongue. The short five-toed legs end with powerful 

 scratching claws, which are excellently adapted for rapid burrowing. 

 Ornithorhynchus, on the contrary, has a close, soft fur, a flattened 



* E. Owen, Article " Monotremata," in Todd's " Cyclopaedia of Anatomy," 

 vol. iii., 1843. 



j- Vide note on p. 296. 



