COLD-BLOODED VERTEBRATA 381 



o 



armour plates, over which the epidermis wears away, very 

 different from the thin rounded cycloid scales which clothe 

 the majority of Teleostomi. It is on some of these 

 ganoid scales that vestiges of the spine occasionally 

 remain. 



All these features, however, disappear in the great mass 



of ordinary bony fishes or Teleostei. The 

 The Cocl' : Whiting (Gadus merlangus), which, with its near 



kindred the Haddock (G. ceglefinus) and Cod 

 (G. morrhua), is often dissected in the laboratory, 1 is a 



Fig. 273. — A diagram of the Haddock. — From Thomson. 



Anus; at/ 1 ., af^., anal fins; &, barbule ; br.m., branchiostegal membrane 

 (a continuation of the gill cover) ; cf., caudal fin ; df.^-d/'K, dorsal fins ; 

 g-., genital opening ; na., nasal openings (double on each side) ; o/>., operculum 

 or gill cover ; J>f., pectoral fin ; pvf., pelvic fin ; «., urinary opening. 



typical Teleostean, both in the above respects and in the 

 very large number of bones which compose its complicated 

 skeleton (Figs. 41 r, 412). In it, as in many others, the 

 pelvic fins have shifted forwards till they lie actually in 

 front of the pectorals, and the air-bladder does not com- 

 municate with the gullet. The Salmon, Herring, Carp, 

 and Eel resemble the ganoids in carrying their pelvic fins 

 in the normal position, and in that the air-bladder com- 

 municates with the gullet, which it does on the dorsal side. 



1 The student who wishes to study systematically one of these three 

 fishes will find on p. 574 a summary of its anatomy with additional 

 figures. 



