FISHES OF THE FAMILY LORICARIIDA. 
ho 
oo 
or 
Two specimens: Guiana. 
Examples in the Museum at Paris, brought from the La Plata River by d’Orbigny 
and named /. itacua by Valenciennes, proved to be Plecostomus commersonii C. & V. 
I have little doubt, however, that the species described and figured by Valenciennes is 
closely allied to Chetostomus megaccphalus Gthr. and may be identical with it. 
18. ANcISTRUS PLATYCEPHALUS. (Plate XII. fig. 4.) 
Chetostomus platycephalus Bouleng. Boll. Mus. Torino, xiii. 1898, no. 329, p. 9. 
Depth of body 53 times in the total length, length of head 24 times. Head a little 
broader than long and 21 times as long as deep. Diameter of eye 11 times in the 
length of head, interorbital width 5} times, length of snout 12 times. Length of 
mandibular ramus equal to 1} times the interorbital width. Head without ridges or 
prominences, flat; snout very broad, rounded; interoperculum with 25-30 spines, the 
longest equal to about } the length of head. Scutes not carinate, the posterior rather 
strongly spinate, 24 in a longitudinal series, 5 between dorsal and adipose fin, 10 
between anal and caudal; supraoccipital bordered posteriorly by a pair of scutes, 
which exclude the first median scute from contact with it; lower surface of head and 
~abdomen naked. D. I 8, the first ray equal to 3 the length of head, the last 4 as long; 
length of base of dorsal a little less than its distance from the caudal. A. I 4. 
Adipose fin well developed. Pectoral spine extending to base of ventral. Caudal 
obliquely truncate. Caudal peduncle 2} times as long as deep. Olivaceous. 
Total length 140 mm. 
A single specimen: E. Ecuador. 
19. ANCISTRUS NIVEATUS. 
Hypostomus niveatus Casteln. Anim. Am. Sud, p. 43, pl. xxi. fig. 3 (1855). 
Chetostomus niveatus Giinth. Cat. Fish. v. p. 243 (1864). 
Hemiancistrus longipinnis* Kindle, Ann. Ac. N. York, vii. 1895, p. 295. 
Depth of body about 44 times in the total length, length of head about 3 times. 
Head as broad as long and 14 times as long as deep. Diameter of eye about 7 times 
in the length of head, interorbital width 2} times, length of snout about 13 times. 
Length of mandibular ramus about 1 times in the interorbital width. Snout broad, 
obtuse; supraorbital edges not raised; supraoccipital flat; temporal plates not 
carinate ; interoperculum armed with numerous long slender spines, with curved tips, 
the longest equal to } the length of head. Scutes spinulose, not carinate, 24 ina 
longitudinal series, 5 between dorsal and adipose fin, 13 between anal and caudal ; 
supraoccipital entirely bordered posteriorly by a single scute ; lower surface of head 
and abdomen naked. D.1 7, the first ray 3 the length of head, the last 3-? as long, 
1 Professor S. H. Gage, of Cornell University, has kindly sent me a drawing of the type of HH. longi- 
vinnis, which seems almost certainly identical with A. niveatus. 
