THE KNELT AND ITS ALLIES 



245 



a number of aberrant forms. Some of these are greatly 

 elongated, like the pipe-fish proper (Fig. 228) ; others are 

 shorter and stouter, like the u sea-horse." All have an 



FIG. 228. Siphostomafuscum, the pipe-fish. Nat. size. Photo, by W. H. C. P. 



elongated snout, and usually a long, slender tail. The 

 body is encased in bony plates, and the male is often pro- 

 vided with a brood-pouch, in which the developing young 

 are carried. 



Besides the bony fishes, which we have just considered 

 in detail, there are various other classes of fish. 



FIG. 22l>. Petromyzon, the lamprey. One-fourth nat. size. After Goode. 



The Cyclostomi, or lamprey eels, are the only parasitic 

 vertebrates. In the adult stage they either live attached 



