264 CLASS MAMMALIA. 



is ample, and almost globular, and their caecum 

 moderate. The penis is terminated by four tuber- 

 cles. There are two species known. 



The Spiny Echidne (Echidna Hystrioc, Ornithorinchus His- 

 trice t Home. Myrmecophaga Aculeata, Shaw.) 



Entirely covered with thick spines. 



The Bristly Echidne (Echidna Setosa), Ornithorinchus 

 Setosus, Home. 



Covered with hair, in which the spines are half 

 hidden. 



The Ornithorincus (Ornithoryncus,) Blumenbach. 

 Platypus, Shaw. 



Their elongated and, at the same time, singularly 

 enlarged and flatted muzzle, gives the greatest ex- 

 ternal resemblance to the beak of a Duck ; the 

 more so, as their edges are furnished with similar 

 small transverse laminae. There are teeth only at 

 the bottom of the mouth, to the number of two on 

 each side, in each jaw, without roots, with flat coro- 

 nals, and composed, like those of the Orycteropus, 

 of small vertical tubes. The fore-feet have a mem- 

 brane which not. only unites the toes, but consi- 

 derably exceeds the nails ; in the hind-feet the 

 membrane terminates at the root of the nails, two 

 characters which, with the flat tail, constitute the 

 Ornithorinci aquatic animals. Their tongue is, in 

 some degree, double; one in the beak studded with 



