FISHES OF THE FAMILY LOEICARILOE. 219 



side. Lower surface of head and abdomen entirely covered with small granular 

 scales. D. I 7, the first ray nearly as long as the head, the last f as long ; length of 

 base of dorsal equal to the length of head. No trace of an adipose fin. A. I 5. 

 Pectoral spine not reaching ventral. Caudal strongly and obliquely emarginate. 

 Caudal peduncle 2£ times as long as deep. Brownish ; a few dark spots on the 

 membrane of the dorsal. 



Total length 225 mm. 



One specimen, in the Paris Museum, from the Upper Amazon. 



24. f Plecostomus genibarbis. 



Rinelepis genibarbis Cuv. & Val. Hist. Nat. Poiss. xv. p. 484, pi. 453 (1840). 



Ananthicus genibarbis Gunth. Cat. Fish. v. p. 253 (1864). 



Rhinelepis agassizii Steind. Sitzb. Ak. Wien, lxxvi. 1878, p. 228; Denkschr. Ak. Wien, xlvi. 1882, 



p. 7; Eigenm. & Eigenm. Proc. Cal. Ac. (2) ii. 1889, p. 42, and Occ. Pap. Cal. Ac. i. 1890, 



p. 416. 



Length of head 3—3^ times in the total length. Head 1-11 times as long as broad 

 and lf-l-f times as long as deep. Diameter of eye 6-8 times in the length of head, 

 interorbital width 2-2f times, length of snout about twice. Scutes carinate, 22-25 in 

 a longitudinal series. Brown, fins dark-spotted. In other characters essentially 

 similar to P. pellegrini. 



R. Amazon. 



Cuvier and Valenciennes' type was a stuffed specimen of 375 mm. The specimens 

 described by Steindachner measure up to 280 mm. in total length. I am convinced 

 that B. agassizii must be identical with B. genibarbis, as the descriptions agree very 

 closely, and the differences are of little importance, the most striking being the more 

 elevated dorsal fin of B. agassizii, due in some degree to the smaller size of the 

 specimens, and probably also 'to the fin being broken in Valenciennes' type, a condition 

 which this author was very prone to overlook or neglect. 



25. Plecostomus parahyb^e. 



Rhinelepis parahybce Steind. Sitzb. Ak. Wien, lxxvi. 1878, p. 218, pi. ii.; Eigenm. & Eigenm. 

 Proc. Cal. Ac. (2) ii. 1889, p. 42, and Occ. Pap. Cal. Ac. i. 1890, p. 415. 



Depth of body about 6 times in the total length, length of head 3-5^ times. Head 

 1^ — 13- times as long as broad and twice as long as deep. Diameter of eye 7 times in 

 the length of head, interorbital width 2-^— 2-f times, length of snout lf-lf times. 

 Length of mandibular ramus 2^- times in the interorbital width. Snout obtuse ; 

 supraoccipital with low median ridge ; opercular plate rather large. Scutes not 

 carinate, 25-26 in a longitudinal series, 11 between anal and caudal ; a group of 

 small granular plates behind the lower part of the temporal plate ; supraoccipital 

 bordered posteriorly by a pair of scutes, which nearly or quite exclude the first 



