220 MR. CO. TATE REGAN ON THE 
median scute from contact with it. Lower surface of head and abdomen naked 
except for a patch of small granular plates in front of each gill-opening, a strip 
between the pectorals, and a lateral series of small plates on each side of the 
abdomen. JD. I 7, the first ray 3-$ the length of head, the last $ as long; length of 
base of dorsal # the length of head. No trace of an adipose fin. A.15. Pectoral 
spine extending a little beyond base of ventral. Caudal slightly emarginate. Caudal 
peduncle 24-2? times as long as deep. Uniformly brownish. 
Total length 300 mm. 
Two specimens: Rio Parahyba. 
26, PLECOSTOMUS ASPER. 
Rhinelepis aspera Spix, Gen. et Spec. Pisc. Bras. p. 4, pl. ii. (1829) ; Cuv. & Val. Hist. Nat. Poiss. 
xv. p. 483 (1840) ; Giinth. Cat. Fish. v. p. 253 (1864). 
Rinelepis strigosa Cuv. & Val. t.c. p. 480. 
Depth of body 4% times in the total length, length of head 2 times. Depth of head 
15 times in its length, breadth of head 14 times, diameter of eye 11 times, interorbital 
width 15 times, length of snout 1¢ times. Length of mandibular ramus 33 times in 
the interorbital width. Head flat above, without keels or ridges; snout obtuse ; 
opercular plate very large. Scutes spinulose, not carinate, 24 in a longitudinal series, 
10 between anal and caudal; a group of small granular plates behind the lower half 
of the temporal plate and the upper part of the clavicle ; supraoccipital bordered 
posteriorly by a median scute or pair of scutes and one on each side ; lower surface of 
head and abdomen completely covered with small granular scales. D. 17, the first ray 
equal to 8 the length of head and to the length of the base of the fin. Adipose fin 
represented by a small rounded plate between the eighth and ninth pairs of scutes 
behind the dorsal. A.I5. Pectoral spine extending to anterior } of ventral. Caudal 
very slightly emarginate. Caudal peduncle twice as long as deep. Colour uniform 
brownish. 
Total length 330 mm. 
One specimen (type of R. strigosa): Eastern Brazil. 
2. HEMIPSILICHTHYS. 
Xenomystus (non Giinth.) Liitk. Vid. Medd. 1878, no. 13, p. 217. 
Hemipsilichthys Kigenm. & Eigenm. Proc. Cal. Ac. (2) ii. 1889, p. 46. 
Similar in most characters to Plecostomus, but the snout with a naked margin, the 
dorsal fin originating above the ventrals, separated from the supraoccipital by 5 scutes, 
and the teeth in the jaws forming curved crescent-shaped series. 
S.E. Brazil. 
