544 MANUAL OF ZOOLOGY. 



rainated by man within a comparatively recent period. This 

 remarkable animal was discovered about the middle of the 

 eighteenth century in a little island (Behring's Island) off the 

 coast of Kamtschatka. Upon this island^he celebrated voyager 

 Behring was wrecked, and he found the place inhabited by 

 these enormous animals, which were subsequently described 

 by M. Stellar, who formed one of his party. The discovery, 

 however, Was fatal to the Rhytina, for the last appears to have. 

 been seen iii the year 1768. The Rhytina was an animal of 

 great size, measuring twenty-five feet in length, and twenty feet 

 at its greatest circumference. There can hardly be said to 



have been any true teeth, but the jaws contained ^^ large 



lamelliform fibrous structures, which officiated as teeth, and 

 may be looked upon as molars. The epidermis was extremely 

 thick and fibrous, and hairs appear to have been wanting. 

 There was a crescentic tail- fin, and the anterior limbs alone 

 were present. 



Order V. Cetacea. — In this order are the Whales, Dol- 

 phins, and Porpoises, all agreeing with the preceding in their 

 complete adaptation to an aquatic life (figs. 213, 214). »The 

 body is completely fish-like in form ; the anterior limbs are con- 

 verted into swimming-paddles or " flippers ; " the proximal 

 bones of the fore-limbs are much reduced in length, and the 

 succeeding bones are shortened and flattened, and are en- 

 veloped in a tendinous skin, thus reducing the limbs to oar- 

 like fins ; there are no external ears ; the posterior limbs are 

 completely absent ; and there is a powerful, horizontally-flat- 

 tened, caudal fin, sometimes accompanied by a dorsal fin 

 as well. In all these characters the Cetacea agree with the 

 Sirenia, except in the one last mentioned. On the other hand, 

 the nostrils, which may be single or double, are always placed 

 at the top of the head, constituting the so-called "-blow-holes" 

 or "spiracles;" and they are never situated at the end of a 

 snout. The body is very sparingly furnished with hairs, or 

 the adult may be completely hairless. The testes are retained 

 throughout life within the abdomen, and there are no vesiculae 

 seminales. The teats are two in number and are placed upon 

 the groin. The head is • generally of disproportionately large 

 size, and is never separated from the body by any distinct 

 constriction or neck. The lumbar region of the spine is long, 

 and, as in the Sirenia, there is no sacrum, and the pelvis is 

 only present in a rudimentary form. There are no clavicles, 

 and some of the digits may possess more than three phalanges 

 each. Lastly, the adult is either destitute of teeth or is mono- 



