372 chaeacinid^;. 



high, and separated from the praeopercular limb by a narrow strip of 

 skin. Abdominal serratnre composed of from thirty-two to thirty- 

 five spinous plates. An indistinct roundish blackish blotch on the 

 commencement of the lateral line ; lower parts of the body with 

 numerous small, round, light dots. (Kner.) 

 Rio Guapore. 



46. MYLETES*. 



Myletes, sp., Cuv. Mem. Mm. iv. p. 444. 



Myletes et Myleus, Mull, tf Trosch. Hor. Ichth. i. pp. 22, 24. 



Myletes, Tometes, et Myleus, Cuv. fy Val. 



Dorsal fin rather elongate, placed behind the middle of the length 

 of the body, between ventrals and anal ; anal long. Head and body 

 compressed, elevated, covered with very small scales ; belly keeled, 

 serrated. Cleft of the mouth rather narrow : teeth large, compressed, 

 with a more or less oblique cutting edge ; those of the intermaxillary 

 are in a double series, those of the mandible in a single, but there is 

 a pair of conical teeth in the middle behind the front series of cutting 

 teeth ; maxillary without teeth. Gill- openings very wide. 



Continental tropical America, east of the Andes. 



The species may be referred to two groups : — 



* The posterior series of intermaxillary teetli separated from the an- 

 terior by an interspace : Myletes, M. & T., p. 373. 



* * Both series of intermaxillary teeth close together : Myleus t, M. & T., 

 p. 377. 



* 1. Myletes acanthogaster. Cuv. <$- Val. xxii. p. 209. — Lake of Maracaibo. 



2. lobatus, Cuv. 8f Val. xxii. p. Iil2. — River Amazons. 



.3. Tetragonopterus scbomburgkii, Jardine, in Schomb. Fish. Guian. i. p. 243. 



pi. 22 ; Myletes scbomburgkii, M. Sf T. Hor. Ichth. p. 37 ; C. $ V. xxii. 



p. 212. — Gruianas. 



4. Palometa du baut Orenoque. Humb. Observ. Zool. ii. p. 177. — Myletes 



palometa, C. 8f V. xxii. p. 214. — Orinoco. 



5. Myletes luna, C Sf V. xxii. p. 221.— Cayenne. 



6. rhomboidalis, Kner, Benkschr. Acad. Wiss. Wien, 1860, xviii. p. 22 



(not synon.). — Rio Parana. 



7. Tometes unilobatus, C. tf V. xxii. p. 229. — Cayenne. 



8. Myletes bidens, C. Sf V. xxii. p. 201 ; Casteln. Anim. Amer. Sud, Poiss. 



p. 68. pi. 35 (skull) (not Spix). — Rio Paraguay. 



9. torquatus, Kner, Denkschr. Acad. Wiss. Wien, 1860, xviii. p. 24. taf. 1. 



fig. 4. — Rio Branco. 



t Kner has shown that the character on which Miiller and Troschel have 

 founded the genus Myleus, viz. the absence of conical posterior mandibulary teeth, 

 is so far from being constant, that it appears rather to have been an accidentally 

 or temporarily abnormal state of the specimens examined by them. 



