95. cn^TOSTOMUS. 245 



one-half of the width of the interorbital space. Margin of the snout 

 granulated, without bristles ; interopcrculum with a bundle of about 

 sixteen sctiform spines, the longest of which are nearly one-third of 

 the length of the head, and extend backwards to the root of the 

 pectoral. Thorax and belly nearly entii-ely naked, being covered with 

 patches of small graniilations only laterally and anteriorly. Dorsal 

 fin higher than long, the length of its anterior rays being more than 

 that of the head ; the length of its base is less than its distance from 

 the caudal; there are seven scutes between the two dorsal fins. 

 Caudal fin forked, the lower lobe being stronger, but not longer than 

 the upper. The pectoral spine extends nearly to the middle of the 

 ventral fin, the ventral fin to behind the anal. Thirteen scutes between 

 anal and caudal. Scutes of the body vrithout a keel ; posthumeral 

 ridge rather indistinct. Bro'wn, all parts covered with round black 

 spots of moderate si^e ; those on the head are smaller than those on 

 the body, those on the fins being the largest ; there is only one series 

 of these spots on each interradial space of the dorsal fin ; the spots 

 on the caudal are as large as the eye. 

 River Capin. 



a. Five inches long. Piu'chased of Mr. Stevens. 



11. Chsetostomus schombnrgkii. 

 D. 1/7. A. 5. P. 1/G. L. lat. 25. 



Head much depressed, a little longer than broad, its length being 

 one-third of the total (without caudal) ; occipital and nuchal regions 

 flat. Snout broad, much depressed, granulated above and on the 

 margin, except in the middle of its extremity, where it is naked ; its 

 margin is without bristles ; interopcrculum with a bundle of about 

 thirty long setiform sjjines, the longest of which is one-third of the 

 length of the head. Eye rather small, its diameter being one-third 

 of the width of the interorbital space. Thorax and belly entirely 

 naked. Dorsal fin scarcely longer than high, the length of its base 

 being a little more than its distance from the second fin ; there are 

 seven scutes between the two fins. Caudal obhquely truncated. The 

 pectoral spine extends just to the base of the ventral. Eleven scutes 

 between anal and caudal. The lateral scutes of the body without 

 any keels, but with the margin slightly serrated. Posthumeral ridge 

 very obtuse. Brownish, clouded with darker ; fin-rays with brown 

 dots. 



British Guiana. 



a-b. Three and a half inches long. Presented by Sir II. Schomburgk. 



12. Chaetostomus guacharote. 

 Hypostomus guacharote, Cuv. 8f Vol. xv. p. 508. 

 D. 1/7. A. 6. P. 1/6. 

 Interoperculum with about twenty setiform spines, the longest of 

 which are oQC-third of the length of the head. Head depressed, with- 



