130 VERTEBRATA. MAMMALIA. 



marsupial bones, and they display many important 

 agreements in their anatomy. They are, moreover, 

 confined to the marsupial regions of Australasia. 

 They are called respectively Echidna,* and Orni- 

 thorhynchus.^ 



They are undoubtedly the lowest forms of Mam- 

 malia known, and are interesting as being the points 

 at which this highly organized class of Vertebrata 

 branches off to the inferior, Reptilia. The elaborate 

 anatomical investigations of Professor Owen and other 

 zoologists have discovered in them many affinities 

 to that class, which were before little suspected. 

 The mode of their generation was long a matter of 

 much uncertainty, but it seems now pretty clearly 

 established that they are ovo-viviparous, (the young 

 being produced in eggs, which are hatched inter- 

 nally,) and that the infant animal is nourished by 

 true milkjj injected by the muscular action of the 

 nipple. The teeth are entirely wanting; the eyes 

 are small ; the ears destitute of an external conch ; 

 the muzzle is protruded into a long beak ; the limbs 

 are short, and adapted for digging: there are five toes 

 to each foot armed with strong claws, and the hind 

 feet have a supernumerary claw or sharp curved spur, 

 the use of which is unknown. 



* 'E^rvaj, echinos, a hedge-hog, 

 f "Ogvis, ornis, a bird, and e vyxos, rhynckos, a beak, 

 t See Proc. Zool. Soc. for 1832, pp. 145, 180; 1833, pp. 30, 82; and 

 1834, p. 44. 



