XVI.] CETACEA. 271 



true Ruminants in the structure of the fore-foot (see Fig. 

 98). In the carpus the trapezoid and magnum are distinct, 

 as in the Suina and Perissodacfyla, whereas these bones are 

 confluent in the Pecora and TragiUiiia. There are no traces 

 of any metacarpals or digits, except the third and fourth. 

 The metacarpals of these are very long and, as in the Pecoj-a, 

 confluent throughout the greater part of their length, though 

 separated for a considerable distance at the lower end. The 

 distal articular surfaces, instead of being puUey-Hke, with 

 deep ridges and grooves, are simple, rounded, and smooth. 

 The proximal phalanges are expanded at their distal ends, 

 and the wide and depressed middle phalanges are imbedded 

 in a broad cutaneous pad, forming the sole of the foot, on 

 which the animal rests in walking, instead of on the hoofs, 

 as in other Ruminants. The ungual phalanges are very 

 small and nodular, not flattened on their inner or opposed 

 surfaces, and not completely encased in hoofs. These 

 characters are better marked in the true Camels than in the 

 Llamas. 



In the animals constituting the order Cetacea, the manus 

 has undergone a special modification, being converted into 

 a simple, flattened, oval or falciform, usually pointed flipper 

 or paddle, showing externally no signs of division into sepa- 

 rate digits, nor any traces of nails or claws. The skeleton, 

 however, consists, as in other Mammals, of a carpus, 

 metacarpus, and either four, or more commonly five, digits, 

 the great peculiarity of which is, that the number of pha- 

 langes is not limited to three, as in all other animals of 

 the class, but may extend even to twelve or thirteen. 



In the Whalebone Whales, a large portion of the 

 skeleton of the hand remains permanently cartilaginous, and 

 the cartilages composing the various carpal bones and pha- 

 langes are confluent or slightly separated from each other 



