46. MYLETES. 375 



included), the length of the head one-tilth ; operculum about thrice 

 as high as long ; infraorbital ring separated from the praeopercular 

 limb by a strip of naked skin. Adipose fin short, rayed ; none of 

 the fin -rays are prolonged. 

 Brazil. 



7. Myletes orbignyanus. 

 Cuv. 8f Val. xxii. p. 220. 



D. 14. A. 32. 



Body elevated, with the lower profile subsemicircular ; upper pro- 

 file of the head concave above the eyes. Anal fin not very high, 

 without lobe in the middle. Scales very small. ( Val.) 



Parana. 



8. Myletes duriventris. 



Myletes duriventris, Cuv. Mem. Mus. iv. p. 451. pi. 22. fig. 2 ; Cuv. fy 

 Val. xxii. p. 206; Casteln. Anim. Amer. Sud, Poiss. pi. 34. fig. 2 ; 

 Kner, Denkschr. Acad. Wiss. Wien, 1860, xviii. p. 21. 

 Tetragonop terns aureus, Spix, Pise. Bras. tab. 31. 

 Myletes aureus, Ayass. in Spix, Pise. Bras. p. 74. 



D. 15. A. 33. V. 8. L. lat. 150. 



The height of the body is contained once and five-sixths in the 

 total length (with the caudal), the length of the head five times. 

 Abdominal serrature composed of thirty-nine simple spinous plates. 

 Dorsal rays not prolonged ; the rays towards the posterior third of 

 the anal fin are longer than the others, forming an obtuse lobe. 

 Adipose fin short. The infraorbital ring is separated from the prae- 

 opercular limb by a strip of naked skin. 



Brazil. 



9. Myletes bidens. 

 Spix, Pise. Bras. p. 75. tab. 32. 



D. 16-17. A. 26-28. V. 9. L. lat. 95. 



The height of the body is contained once and three-foarths in the 

 total length (without caudal), the length of the head thrice and one- 

 sixth ; operculum thrice as high as long. Abdominal serrature com- 

 posed of fifty-four spinous plates. Adipose fin very short. The 

 outer profiles of the dorsal and anal fins convex. Coloration uniform. 



Northern Brazil. 

 a. Half-grown. From the Collection of the Zoological Society. 



10. Myletes ellipticus. 



D. 27-29. A. 39. V. 7. 



The height of the body is contained once and three-fifths in the 

 total length (without caudal), the length of the head thrice and 

 one-third or thrice and two-thirds. The upper and lower pro- 

 files are nearly equally curved, the outlines of the body forming an 



