618 BIOLOGY. 



tissue, at another to the fins, now to the teeth or to the 

 scales, ay, even to the fin-rays, and all this because the 

 characteristic or typical organ has never been sought 

 after, nor the presence of such an organ as indispensable 

 been so much as known. 



3534. The characteristic organ of Fishes is the Osseous 

 system, which is consequently the principle also of their 

 division. 



The physical nature, form, position, and number of 

 the osseous parts must therefore be principally considered, 

 and hence, above all, the substance or texture of the 

 bones ; the limbs also, and the maxilla with their teeth, as 

 well as the teeth upon the palate, upon the tongue and 

 the branchial arches. 



With regard to the component substance or texture of 

 the bones we encounter a great difficulty. The Cartilagi- 

 nous Fishes appear to belong to each other, and are 

 also usually arranged together. Yet amongst them we 

 find those species, such as the Lampreys, which obvi- 

 ously occupy the lowest grade of all Fishes, while the 

 Sharks and Rays remind us of the Reptilia and Thricozoa, 

 as well by their external structure as the development of 

 their sexual parts, since they possess perfect testes, and 

 ovaria separate or distinct from the oviducts, while they 

 no longer deposit roe, but large ova inclosed in leathery 

 shells, like the higher Reptilia. Now, if we separate 

 these Fishes from the Lampreys, with whom in the scale- 

 less tegument, the branchial foramina, and even the 

 external form they have many points of resemblance, 

 nothing else remains to be done than assign them the 

 uppermost place, and so parallelize them with the 

 Thricozoa. But one is next constrained to unite into 

 one family the Pikes and Herrings, which perhaps admits 

 of being done. 



There belong namely to the upper Fishes without 

 doubt the Abdominales, which are divisible into five 

 families : the Carps, Pikes, Shads, Salmons, and Herrings. 

 Now, if the Sheat-fishes be placed inferiorly on account of 

 their scaleless body and amorphous maxillae, four families 



