474 EXPLANATION 



/8. Operculum. 



y. Suboperculum. 



J- Intcroperculum. 



8- Postmandibulary. 



^- Mandiliulary. 



'^- Os Ilyoidts bearing the branchial rays. 



Plate VII represents new species of ordinary genera. 



Fig. 1. Diudon anlennritus, Cuv., so called from the circum- 

 stuiice of its bearing several fleshy filaments on the fore part of 

 the head, at a.a.a. as well as on other parts of its body, which 

 are independent of its spines. Its colour is a russet grey, with 

 dark russet spots, arranged symmetrically. 



Fig. 2. Balistes geographicus, Peron. So named from its 

 spots. It belongs to the first division of my Monocanthi. 



Fig. 3. Balisles penicilligerus, Peron. So called from the ra- 

 mose tentacula with which its body is bristled. It belongs to 

 the third division of my Monocanthi. 



Plate VIII. We have left here certain species of fishes, 

 which, at the time of the publication of our first edition, 

 formed new genera or subgenera. 



Fig. 1. Myletes macropomus, Cuv. One of the three species 

 of American Myletes mentioned in the note to that genus. This 

 one is distinguished by the largeness of its opercula. 



Fig. 2. Hydrocyon brevidens, Cuv. This species, which is 

 from Brazil, is also mentioned in a note to the genus under 

 which it is placed. Its specific character consists in being 

 striped longitudinally with blackish. 



Fig. 3. Pristigaster. A subgenus of the family of the Clupeae 

 This species is entirely silvery. 



Fig. 4. Sudis gigas. An extremely large Brazilian species 

 remarkable for its bony scales and the shortness of its tail. 



Plate IX. Two species of Sternoptyx, the first of which, 

 Sternoptyx diaphana^ has hitherto only been known from a 

 bad figure by Hermann. The second is new, and was disco- 

 vered in the vicinity of the Azores by M. Olfers. 



The Gymnai'chus senegalensis is a new species of a 

 genus recently discovered in the Nile by M. Rifaud. 



Plate X, Fig. 1, JVotarchus. A new genus of the Gastero- 

 poda Tectibranchiata. 



