FISHES OF THE FAMILY LORICARIID@. 207 
surface of head and abdomen, in the adult, almost completely covered with small 
granular scales. D. 17, the first ray about as long as the head, the last 4-3 as long; 
length of base of dorsal equal to its distance from posterior part of spine of adipose 
fin. A.1I4. Pectoral spine extending beyond base of ventral. Caudal moderately 
emarginate, the outer rays scarcely produced. Caudal peduncle 54-4 times as long as 
deep. Numerous dark spots on head, body, and fins, those on the head the smallest, 
those on the dorsal in 2—4 series on each interradial membrane, those on the caudal 
usually indistinct. 
Total length 460 mm. 
Twelve specimens (including the type of the species and a co-type of P. limosus) : 
Rio La Plata and its tributaries; Rio Grande do Sul. 
3. PLECOSTOMUS PUNCTATUS. 
Hypostomus punctatus Cuv. & Val. Hist. Nat. Poiss. xv. p. 493 (1840). 
Hypostomus subcarinatus Casteln. Auim. Am. Sud, p. 42, pl. xxi. fig. 1 (1855). 
Plecostomus punctatus Giinth, Cat. Fish. v. p. 233 (1864). 
Plecostomus affinis Steind. Sitzb. Ak. Wien, Ixxiv. 1876, p. 685. 
Plecostomus commersonii Kigenm. & Kigenm. Proce. Cal. Ac. (2) 1. 1888, p. 168, and Occ. Pap. Cal. 
Ac. 1. 1890, p. 403. 
Depth of body 5-6 times in the total length, length of head about 54 times. Depth 
of head 13-1} times in its length, breadth of head 1§-1} times, diameter of eye 
6-83 times, interorbital width 23-24 times, length of snout 1} times. Length of 
mandibular ramus 24-5 times in the interorbital width. Snout ovate, more or less 
narrowed anteriorly ; supraorbital edges not raised; supraoccipital with low median 
ridge; temporal plates not carinate. Scutes spinulose, the anterior carinate, 28-30 in 
a longitudinal series, 9 between dorsal and adipose fin, 14-16 between anal and caudal. 
Supraoccipital entirely bordered posteriorly by a single scute. Lower surface of head 
and abdomen, in the adult, almost completely covered with small granular scales. 
D. I 7, the first ray as long as or a little longer than the head, the last 3-3 as long; 
length of base of dorsal nearly equal to its distance from the adipose fin. A. I 4. 
Pectoral spine extending to anterior 4 of ventral. Caudal emarginate. Caudal 
peduncle 33-43 times as long as deep. Numerous small dark spots on head, 
body, and fins, those on the dorsal (in the adult) in 2 series on each interradial 
membrane. 
Total length 500 mm. 
Twelve specimens (including the types of the species and of Hl. subcarinatus): 
Southern and Eastern Brazil. 
Under the names P. commersonii affinis and P. commersonit scabriceps, Kigenmann 
distinguishes two varieties of this species, which are said-to have larger spots than the 
typical P. punctatus, the second also having a large naked area on the head behind the 
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