STERNARCHIDiE. PETROMYZONID^. 337 



Family 3. STERNARCHID^. 



Body linear^ anguilliform, but compressed, and often 

 with small scales. 



Gymnotus Bloch. Branchial aperture before the pec- 

 torals ; anal fin very long, and reaching to the end of 

 the tail ; dorsal fin wanting. 



G. electricus. Bloch, 156. 



Gymnarchus Cuv. Body elongated, scaly ; gills only 

 sKghtly open ; head conic, naked ; mouth small, with 

 a single row of small cutting teeth ; dorsal fin very 

 long, the rays soft ; anal fin none ; tail pointed. 

 G. niloticus Cuv. 



Carapus Cuv. Body and head compressed, as in ordi- 

 nary fishes ; tail very long and gradually attenuated ; 

 gill-covers distinct ; pectoral fin present _; anal fin 

 narrow, and reaching to the point of the tail ; dorsal, 

 caudal, and anal fins wanting. 



C. brachyurus, Bloch, pi. 1 57. fig. 1 . macrourus, lb. fig. 2. 



Sterna7'chus Sch. General habit of the last ; head ob- 

 long, compressed, naked ; the skin concealing the 

 opercula ; body scaly ; teeth close, even ; anal fin 

 distinct from the caudal. 



S. albifrons, Pallas. Sp. Zool. pi. 6. fig. 1. 



Leptocephalus Pal. Body greatly elongated, and re- 

 markably compressed ; head very small ; snout short, 

 and somewhat pointed; pectoral fins very small; 

 caudal, dorsal, and anal fins united. 



L. Morrisii. Yarrell, Brit. F. pi. at page 311. 



Family 4. PETROMYZONID.^. Lampreys. 



Body elongated ; eyes very small or none ; mouth cir- 

 cular, placed beneath the head and opening by a longi- 

 tudinal fissure; skeleton soft, almost mucilaginous; 

 branchial spiracles two or more. 



Amphioxus Yarrell. Body compressed, lanceolate, hy- 

 aline ; a single dorsal fin the whole length of the 



VOL. II, Z 



