226 ME. C. TATE BEGAN ON THE 



2. Ancisteus UNDECIMALIS. 

 Chcetostomus undecimalis Steind. Denksckr. Ak. Wien, xxxix. 1878, p. 43, pi. viii., and xlii. 1880, 



p. 67. 

 Pterygoplichthys undecimalis Eigenm. & Eigenm. Proc. Cal. Ac. (2) ii. 1889, p. 44. 



Depth of body i\ times in the total length, length of head 3^ times. Head 1^ times 

 as Ion" - as broad and If times as long as deep. Diameter of eye 1\ times in the 

 length of head, interorbital width 2\ times, length of snout twice. Length of mandi- 

 bular ramus about 4 times in the interorbital width. Snout narrowed anteriorly; 

 supraoccipital with median ridge ; supraorbital edges not or scarcely raised ; temporal 

 plates carinate ; interoperculum armed with 6-8 slender spines, the longest equal to 

 \ the length of head. Scutes spinulose, carinate except on the caudal peduncle, 

 28-29 in a longitudinal series, 8-9 between dorsal and adipose fin, 12-13 between 

 anal and caudal. Supraoccipital entirely bordered posteriorly by a single scute ; two 

 series of scutes between the nuchal and posthumeral series. Lower surface of head 

 and abdomen completely covered with small granular scales. D. I 10, the first ray 

 equal to f the length of head, the last f as long ; length of base of dorsal equal to its 

 distance from the caudal. A. I 3-4. Pectoral spine extending nearly to middle of 

 ventral. Caudal emarginate, the shortest ray § the length of the longest, which is 

 1^ times as long as the head. Caudal peduncle 3 times as long as deep. Greyish, 

 with dark spots on head, body, and fins, those on the head smallest, those on the fins 

 in a single series between each pair of rays. 

 Total length 230 mm. 



One specimen : R. Magdalena. 



3. Ancistkus etentaculatus. 



Hypostoma etentaculatum Spix, Gen. Spec. Pise. p. 7, pi. iv. figs. 1 & 2 (1829). 

 Hypostomus duodecimalis Cuv. & Val. Hist. Nat. Poiss. xv. p. 498, pi. ccccliv. (1840). 

 Ancistrus lonyimanus Kner, Denkschr. Ak. Wien, vii. 1854, p. 283. 

 Pterygoplichthys duodecimalis Giintlt. Cat. Fish. v. p. 251 (1864). 



Pterygoplichthys etentaculatum Eigenm. & Eigenm. Proc. Cal. Ac. (2) ii. 1889, p. 44, and Occ. 

 Pap. Cal. Ac. i. 1890, p. 428. 



Depth of body 4J times in the total length, length of head 3 times. Head 1^- times 

 as long as broad and 1-|- times as long as deep. Diameter of eye nearly 8 times in the 

 length of head, interorbital width 2\ times, length of snout 1^ times. Length of 

 mandibular ramus 3 J times in the interorbital width. Snout narrowed anteriorly; 

 supraoccipital with median ridge ; supraorbital edges slightly raised ; temporal plates 

 carinate ; interoperculum armed with 10-12 slender spines, the longest equal to \ the 

 length of head. Scutes spinulose, carinate except on the caudal peduncle, 28 in a 

 longitudinal series, 6 between dorsal and adipose fin, 12 between anal and caudal. 

 Supraoccipital entirely bordered posteriorly by a single scute ; two series of scutes 



