350 FISHES. 



the same as that of the trunk, its extremity being provided with 

 a low fin above and below, similar in form to a dorsal and anal 

 fin. Anal fin very low. 



Three species are known : Ch. monstrosa, from the coasts 

 of Europe and Japan and the Cape of Good Hope ; Ch. colliei 

 from the w^est coast of North America ; and Ch. affinis from 

 the coast of Portugal. (See Fig. 96, p. 184.) 



Callokhynchus. — Snout Avith a cartilaginous prominence, 

 terminating in a cutaneous flap. Two dorsal fins, the anterior with 

 a very strong and long spine. Extremity of the tail distinctly 

 turned upwards, Avith a fin along its lower edge, but without one 

 above. Anal fin close to the caudal, short and deep. 



One species (C. antardicus) is common in the Southern 

 temperate zone. Cunningham describes the egg (see Eig. 81, 

 p. 169), as being of a dark greenish-black colour, and, in 

 aeneral, measuring from eight to nine or even ten inches in 

 length, by about three in breadth. It consists of a central, 

 somewhat spindle-shaped convex area (between the horny 

 walls of which the young fish lies), surrounded by a broad 

 plicated margin, which is fringed at the edge, and covered on 

 the under surface wdth fine light brownish-yeUow hairs. 



SECOND OKDER— GANOIDEI. 



Sheldon cartilaginous or ossified. Body loith medial and 

 paired fins, the hinder jmir ahdominal. Gills free, rarely 

 partially atfaehcd to the walls of the gill-cavity. One external 

 gill-Oldening only on each side ; a gill-cover. Air-hladder with 

 a pneumatic duct. Ova small, impregnated after exclusion. 

 Emhryo sometimes with external gills. 



To this order belong the majority of the fossil fish re- 

 mains of palaeozoic and mesozoic age, whilst it is very 

 scantily represented in the recent fauna, and evidently verging 

 towards total extinction. The knowledge of the fossil forms, 

 based on mere fragments of the hard parts of the body only. 



