472 MONOtREMATA. 



geograj)liical extent to x\ustralia and its islands, so 

 peculiarly organised, tliat they may be considered as 

 forming a connecting link between tlie true Mammals 

 and the Oviparous Vertebrata, and to these remarkable 

 quadrujDeds we must next beg the reader's attention. 



Sub-Class. — Ovo-vivipara.* 



Order I. — Monotremata.! 



The broad characters whereby a bird is distin- 

 guishable from a Mammiferous animal, as we have 

 endeavoured to show, are plain and simple enough. 

 The bird lays eggs and incubates them. The Mam- 

 mal produces its young alive, and suckles them, yet 

 strange to say, there are certain creatures so exactly 

 intermediate in their organization between these two 

 great classes, that even the anatomist has hesitated 

 as to which of them they were strictly referable, 

 although close research has at length decided their 

 place to be among the Mammalia. 



The Duck-billed Platypus J {Ornithorynclms ^ %)aradoxus\\) is a 

 quadruped, about two feet in length, with a rounded, flattened body, 

 covered with short, soft fur, of a deep-brown hue ; it has a broad, flat 

 tail, very short legs, and the toes are united by a web, which in the 

 forefeet spreads out considerably beyond the tips of tlie claws. This 

 formation enables it to swim with ease and grace ; but as it also bur- 

 rows in the earth, the free part of the web folds back when the 

 animal is thus engaged, and leaves the claws unencumbered. The 

 muzzle very much resembles the broad flat bill of some of the ducks ; 

 it is covered with a blackish skin, which overlaps at the edges, and 

 folds back at the base into a broad margin. The place of molar teeth 

 is supplied by eight broad, horny excrescences (two on each side of 

 each mandible), of an irregular form, which probably serve as 



* Ovum, an egg; viviparus, giving hirth to living offspring — so 

 called because it is problematical whether they produce eggs or living 

 young. 



t H-ovos, monos, single; Tprifia, trema, an orifice — i.e., ha\'iug a 

 single excretory and generative outlet. 



i TTKarvs, platus, hroad ; ttovs, pons, afoot. 



^ opviSy opviQos, ornis, ornithos, a hird ; pu7xos, rynchos, a healc. 



II Paradoxical. 



