PISCES. 323 



62. MUR^ENA Gills opening by a small aperture 



on each side : pectorals wanting : dorsal and anal uniting 

 at the tail; low, sometimes scarcely distinguishable. 



63. LEPTOCEPHALUS Gill-opening small, before 



the pectoral : body very much compressed, ribband-shaped : 

 head extremely small; snout short: pectorals scarcely per- 

 ceptible : dorsal and anal obsolete, uniting at the extremity 

 of the tail. 



64. OPHIDIUM. Gills opening by a moderately large 

 aperture ; furnished with a distinct opercle and branchioste- 

 gous membrane : body very much compressed : dorsal and 

 anal uniting to form a pointed caudal ; the dorsal rays arti- 

 culated, but not branched. 



65. AMMODYTES. Gill-opening very large ; all the 

 pieces of the opercle considerably developed : snout sharp ; 

 upper jaw capable of great extension, but when at rest 

 shorter than the lower : dorsal and anal separated from 

 the caudal by a small space; the dorsal furnished with 

 simple articulated rays: caudal forked. 



ii. LOPHOBRANCHII. Branchia in small 

 round tufts disposed in pairs along the branchial 

 arches ; opercle large, confined on all sides by 

 a membrane, with only a small hole for the 

 external aperture; branchiostegous rays rudi- 

 mentary: jaws complete, and free. 



ORDER III. OSTEODERMI. 



Body mailed with transverse angular plates: snout 

 very much produced, formed by a prolongation of 



x2 



