176 



ZOOLOGY. 



four eyes^ though but two orbits^ yet as each 1g furnished 

 with two pupils^ the effect must be supposed the same, as if 

 each pupil was placed in a separate orbit. 



3. Amia. Head flattened, rough, bony, naked ; teeth nu- 



merous, sharp, erect, situated in the jaws, and palate; 

 cirri two, placed near the nostrils ; body scaly ; gill- 

 membrane twelve rayed, 



4. Silarus. Silure. J/e«J large, broad, depressed, naked ; 



mouth furnished with long tentacula ; gape exceeding- 

 ly wide, extending nearly the whole length of the 

 head ; body compressed, elongated, without scales, 

 slippery ; gill-membrane from four to seven rayed ; the 

 first ray of the pectoral or first dorsal fm^ spinous ; 

 spines recurved. 



5. Plafystachus, Mouth beneath, bearded ; body without 



scales, depressed; tail long, compressed; m general 

 habits and aspect nearly allied to the last genus ; like 

 w hich, all the species are marine. 



6. Loricaria. Head smooth, depressed ; moutT\ retractile ; 



teeth wanting ; gill-membrane six rayed ; body covered 

 with plates. 



7. Salmo. Salmon. Rays in the gill-membrane^ from 



four to ten ; teeth in the jaws, and on the tongue ; 

 dorsal fins two ; the hinder one thick, fleshy, and 

 without rays. 



