620 BIOLOGY. 



In others they advance to the rear of the thoracic fins, 

 and are even attached to what has been called the " girdle" 

 or humerus Thoracici. 



In others they even get in front of the thoracic fins on 

 the throat Jugulares. 



Lastly, they are actually wanting Apodales. 



In the Lampreys there are neither thoracic nor ventral 

 fins. 



The skeleton of Pishes is not simply divided to a 

 greater extent than in other animals, but has actually a 

 greater number of bones, such as the rays in the perpen- 

 dicular fins, which are wanting in all animals, even in 

 the Reptilia. An animal with dorsal rays must surely 

 be placed among the Fishes, and consequently the 

 Lepidosiren also. 



The misshapen Fishes will therefore occupy the lower 

 stages, the regular the upper, not directly by reason of 

 their form alone ; but because the other organs are also 

 more imperfectly developed, the bones being cartilaginous, 

 the tegument asquamous, mucous, or covered with spines, 

 scutes, and plates; the fins wanting or abortive, or dis- 

 placed from their proper situation ; the head dispropor- 

 tionate in size to the body, the mouth wide or narrow, 

 the eyes placed superiorly or upon the forehead. 



A lower character is afforded also by very long dorsal 

 fins, such namely as extend from the head to the tail. 

 In the Abdominales, Sturgeons, Sharks, and Rays, the 

 perpendicular fins are small ; in the Thoracici, Jugulares, 

 and Apodes they are, on the contrary, mostly very long. 



Moreover, a lower character is a very long coccygeal 

 or caudal fin, which denotes that the anus lies far forwards, 

 and therefore that the tail has a great preponderance 

 over the trunk. In the Abdominales and the Sharks the 

 tail is short ; in the Rays thin and terminated abruptly, 

 as in Reptiles and Thricozoa, Thus the higher the 

 animals ascend the more does the tail diminish in length. 



Regard being had to all these relations, the Irregular 

 Fishes must be viewed as those which correspond to the 

 lower classes of animals, and the Cartilaginous Fishes 



