236 ME. C. TATE REGAN ON THE 



connected by a membrane to the 3 scutes following it. Length of base of dorsal a 

 little more than its distance from the caudal. A. I 4. Pectoral spine extending to 

 middle of ventral. Caudal obliquely and weakly emarginate or truncate. Caudal 

 peduncle about 2f times as long as deep. Large round white spots on head, body, 

 and fins. 



Total length 280 mm. 



Two specimens, stuffed (types of the species): R. Araguay ; R. Tocantins. 



20. f Akcisteus punctatissimus. 



Cheetostomus punctatissimus Steind. Denkschr. Ak. Wien, xliii. 1881, p. 121, pi. iii. fig. 3. 

 Parancistrus punctatissimus Eigeiiin. & Eigenm. Proc. Cal. Ac. (2) ii. 1889, p. 44; Occ. Pap. 

 Cal. Ac. i. 1890, p. 423. 



Depth of body about 5 times in the total length, length of head 3 times. Depth of 

 head about If times in its length, diameter of eye 6 times, interorbital width 3 times. 

 Snout rounded anteriorly ; supraorbital edges slightly raised ; supraoccipital flat, 

 without median ridge ; temporal plates not carinate ; interoperculum armed with 

 slender spines, the longest equal to about twice the diameter of eye. Scutes spinulose, 

 not carinate, 22 in a longitudinal series, G between dorsal and adipose fin, 11 between 

 anal and caudal. Supraoccipital bordered posteriorly by a median scute and by one 

 on each side. Lower surface of head and abdomen naked. D. I 7, the first ray r equal 

 to about -f the length of head, the last about § as long, and entirely connected by 

 membrane to the spine of the adipose fin ; length of base of dorsal greater than 

 its distance from caudal. A. I 4. Pectoral spine extending beyond base of ventral. 

 Caudal weakly and obliquely emarginate. Caudal peduncle twice as long as deep. 

 Brown, with white or light blue clots on head, body, and fins. 



R. Amazon. 



The above is taken from Steindachner's description and figure of a specimen 

 135 mm. in total length. 



21. Ancistrus aueantiaccs. 



Hypostomus aurantiacus Casteln. Anim. Am. Sud, p. 43, pi. xxi. fig. 2 (1855). 



Hypostomus nigricans Casteln. t. c. p. 44, pi. xxii. fig. 1. 



Hypostomus vicinus Casteln. t. c. p. 45, pi. xxiii. fig. 1. 



Parancistrus aurantiacus Bleek. Ned. Tijd. Dierk. i. 1863, p. 79. 



Cheetostomus aurantiacus Giinth. Cat. Fish. v. p. 246 (1864). 



Cheetostomus nigricans Guntli. 1. c. 



Parancistrus nigricans Eigenm. & Eigenm. Proc. Cal. Ac. (2) ii. 1889, p. 44. 



Depth of body about 4^ times in the total length, length of head 2f-2f- times. 

 Head broader than long and If- 2 times as long as deep. Diameter of eye 6-8 times 

 in the length of head, interorbital width 2f-2f times, length of snout If times. 



