SOUTH AMERICAN NEMATOGNATHI. 395 



LXXXI. Neoplecostomus. 



Xeojjlecosiomus Eigenm. & Eigenm. Proc. Cal. Acad. 

 2d Ser. i, 170, 171, 1888 {micro2Js); id., 1. c, ii, 42, 1889. 



Type: Plecostomus microps Steindachner. 



This genus is very closely related to Plecostomus from 

 which it differs in the general form, the number of the 

 fin rays, the granulation of the ventral surface and the 

 position of the adipose fin. 



ANALYSIS OF THE SPECIES OF NEOPLECOSTOMUS. 



a. A. 8 granosuH .342. 



aa. A. 6. microps 343. 



342. Neoplecostomus granosus. 



Hypostomus granosus Ciw. & Val. Hist. Nat. Poiss. xv, 502, 1840 



(Cayenne). 

 Plecostomus granosus Gtinther, v, 237, 1864 (copied). 

 Neoplecostomus granosus Eigenm. & Eigenm. Proc. Cal. Acad. 2d 



Ser. ii, 42, 1889. 

 Habitat: Cayenne. 



This species is known only from the types; as far as 

 we are able to judge, it agrees with N. rnicro'ps in all 

 characters but the number of the anal rays. 



343. Neoplecostomus microps. 



Plecostomus microps Steindachner. Stisswasserf. Stidostl. Bras, iii, 

 130, pi. xiii (Rio Janeiro); Eigenm. & Eigenm. Proc. Cal. Acad. 

 2d Ser. i, 170, 171, 1888 (Juiz do Fora, Rio Parahyba; Goyaz). 



Habitat: Rio Janeiro; Rio Parahyba; Goyaz. 



Head broad, flat, parabolic in front; interorbital region 

 flat; an indistinct ridge from the eye to the nares, no 

 ridges or crests on the postorbital portion of the head. 

 Occipital bone rounded behind, margined by about three 

 nuchal plates; about five plates between the occipital and 

 the dorsal fin. Plates not keeled. 



Tail terete. 



Sides of the head with rather large plates. Tip of snout 

 naked. Twelve teeth on each side of the upper jaw; 

 16 teeth on each side in the lower. 



