FISHES. 3&9 



65. AcHiRUS- Destitute of pectoral fins. Pleuronectes 

 achirus. 



(3). Ventral fins wanting. Apodal. 

 a. Gill opening small, and the gill cover concealed by 

 the skin. 



(aa.) With dorsal fins. 



66. MuR^NA. In this great natural group the fiallow- 

 ing subgenera have been indicated : 1. Anguilla {M. an- 

 guilla). 2. Conger (J/, conger). 3. Ophisurus {M. ser- 

 pens). 4. Muraena (M. helena). 5. Sphagebranchus (S. 

 imberhis). 6. Apterichtes {M. caeca). 7. Synbranchus 

 (^S. marmoratus). 8. Alabes, Cuv. In these subgenera 

 many important characters, for their methodical distri- 

 bution, present themselves to those who have access to 

 specimens or figures of the different species. In the An- 

 guilla the pectoral fins are large, in the Muraena they 

 are wanting. In some the anal and dorsal fins are oblite- 

 rated. In the Anguilla, the gill openings are lateral ; in 

 Sphagebranchus they are jugular, and in Synbranchus and 

 Alabes, they are jugular and united. 



67. Leptocephalus. Body compressed like a ribband. 

 L. Morrisii^. 



(bb). No dorsal fin. 



68. Gymnotos. Anus placed anteriorly, and the anal 

 fin extending along the greater part of the belly, 1. Gy- 

 mnotus {G. electricus). 9,. Carapus (G. macrourus). 3. 

 Sternarchus {G. albifrons). 



h. Gill opening and gill-lid apparent, and of the ordi- 

 nary form. Articulated rays of the dorsal fin simple. 



69. Ophidium. Anal, dorsal, and caudal fins united. 



• Wern. Mem. ii. p. 436. tab. xxii. f. 1. 



