FISHES OF THE FAMILY LORICAKIIDiE. 265 



4. Htpoptopoma joberti. 



Hypoptopoma bilobatum (non Cope) Steind. Denkschr. Ak. Wien, xli. 1879, p. 45, pi. v. fig. 2. 

 Otocinclus joberti Vaill. Bull. Soc. Philorn. (7) iv. 1880, p. 147. 



Length of head 2f times in the total length. Diameter of eye 5f times in the length 

 of head, interorbital width If times. 23-24 scutes in a longitudinal series ; adipose fin 

 present, feeble ; in other characters similar to the preceding species. 



Total length 78 mm. 



A single specimen : Upper Amazon ; R. Jurua. 



After examination of the type of 0. joberti I am fairly certain of its specific identity 

 with the specimen figured by Steindachner as H. bilobatum, 



5. f Htpoptopoma steindachneri. 



Hypoptopoma thoracatum Steiad. Denkschr. Ak. Wien, xli. 1879, p. 47, pi. vi. fig. 1 ; Eigenm. 



& Eigenm. Proc. Cal. Ac. (2) ii. 1889, p. 40, and Occ. Pap. Cal. Ac. i. 1890, p. 389. 

 Hypoptopoma steindachneri Bouleng. Proc. Zool. Soc. 1895, p. 527. 



This species, as described and figured by Steindachner, seems to differ from the 

 preceding in the shorter body (depth 5 times in its length ; caudal peduncle 2-f times 

 as long as deep), longer pectoral spine (extending to the first anal ray), and in the 

 absence of spots on the fins. 



The specimen figured, from the Rio Negro, is 78 mm. in total length. 



6. f Hypoptopoma gulare. 



Hypoptopoma gulare Cope, Proc. Am. Phil. Soc. xvii. 1878, p. 679. 



Very closely allied to the two preceding species, differing apparently in having a 

 single plate in front of the clavicles instead of a transverse series of 4. Dorsal brown 

 at the base, with some dark spots on its middle. Caudal brownish, with a light 

 margin. 



Marahon, Upper Amazon. 



TO. Otocinclus. 



Otocinclus Cope, Proc. Ac. Philad. 1871, p. 283 ; Eigenm. & Eigenm. Proc. Cal. Ac. (2) ii. 1889, 



p. 41, and Occ. Pap. Cal. Ac. i. 1890, p. 392. 

 Hisonotus Eigenm. & Eigenm. Proc. Cal. Ac. (2) ii. 1889, p. 40, and Occ. Pap. Cal. Ac. i. 1890, 



p. 390. 

 Parotocinclus Eigenm. & Eigenm. t. c. p. 41, and t. c. p. 392. 

 Microlejndog aster Eigenm. & Eigenm. t. c. p. 42, and t. c. p. 394. 



This genus differs from the preceding in the structure of the temporal plate, which 

 is perforated like a sieve ; there is also an enlarged foramen at the posterior margin of 

 the temporal plate and another in the axil of the pectoral spine. Eyes placed rather 

 low or moderately high. Dorsal above or behind the ventrals, with I 7 rays, anal 



2n2 



