V 



THE CHIM^ROIDS 



ChimtEROIDS are shark-like in their general characters, 

 but cannot be looked upon as in any strict sense closely 

 associated with the Elasmobranchs. They constitute the 

 second of the more important groups of fishes. Their 

 typical representative is the Chimaera, spook-fish, or sea- 

 cat (Fig. 119). 



StnicUiral Characters 



The typical structures of Chimsera are shown in the dis- 

 section given in Fig. 104. Its thick, round, and blunted 

 head tapers away gradually to the tip of a diphycercal tail, 

 C. The body surface is generally smooth. The paired fins 

 are somewhat shark-like, but their dermal margins have be- 

 com.e greatly enlarged, tapering distally to an acute point ; 

 the foremost dorsal fin provided with an anterior spine folds 

 like a fan and may be depressed into a sheath, SH, in the 

 body wall ; this fin and the hinder ones are largely dermal, 

 D\ basal and radial supports existing only at B\ R'. The 

 gill arches, BA, may be seen to be closely drawn together; 

 their outer openings are now reduced to the slit-like aper- 

 ture beneath the dermal flap, OP. Teeth exist in the 

 form of dental plates, closely fused with the jaws ; as 

 shown in the figure, Z>, three of these occur in each side, 

 a single one on the mandible, an anterior and posterior on 



99 



