9() Ur. C. T. Regan on 



the last mentioned faet, and of the insnflfieieney of the 

 spcciHc diajjjnosis, I left C. trinitutls as a doubtful synonym 

 of A. (/Kacbai'ote ; but it is quite probable that this species 

 may prove to be nearer to A. megacephaliis or A. Bachi, 

 since Dr. Gill does not make any mention of the bristles 

 Avhich are found external to the intcropcrcular spines in 

 A. quacharote and its allies. 



The British Museum has recently received examples of a 

 new species of this genus, which 1 propose to call 



Ancistrus BovaU'i'i, sp. n. 



Allied to A. Schomhurgkii, Giinth. Depth of body about 

 7 in the length, length of head 3. Head nearly as broad as 

 long and 2.^-2| as long as deep. Diameter of eye Q-7^ in 

 the length of head, iuterorbital width about 3, length of 

 snout nearly 2. Snout broad, rounded ; supraorbital edges 

 not raised ; supraoccipital flat, without median ridge ; 

 temporal plates not carinate; iuteroperculum armed with 

 about 15 slender but rather sliort spines, with curved tips. 

 Mouth small, with only 5 or 6 teeth on each side in both 

 jaws ; length of mandibular ramus considerably less than ^ 

 the iuterorbital width. Scutes spinulose, not carinate, 24 

 to 26 in a longitudinal scries, 7 to 9 between dorsal and 

 adipose fin, 11 to 13 between anal and caudal. Supra- 

 occipital bordered posteriorly by a pair of scutes. Lower 

 surface of head and abdomen naked (in the young). Dorsal 

 I 7, the first ray about | the length of head, the length of 

 the base less than the distance from adipose fin. Anal I 4-5. 

 Pectoral spine extending to the base of ventral. Caudal 

 oljli(|uely emarginate. Caudal peduncle about 3 times as 

 long as deep. Olivaceous, visually with darker transverse 

 bars or irregular marbling ; fins usually with dark spots. 



Seven specimens, measuring up to 55 mm. in total length, 

 from the Kaat River, tributary to the Treng River, Upper 

 Potaro, British Guiana, collected and presented to the British 

 Museum by Dr. C. Bovallius, who captured them "in a rapid 

 on the under side of stones." 



Eigenmann has proposed to restrict the name Xenocara to 

 the species without tentacles on the snout, i. e. X. latifrons 

 and X. gymnorliynclms. He would use the name Ancistrus 

 for the species with tentacles ; but, as has been shown above, 

 this is inadmissible, and as it seems useful to distinguish 

 these species by a subgeneric name, I propose Thysanocara 

 lor Xenocara cirrhosuiH and its allies. 



