95. cii^ETOsTOMtrs. 249 



** Snout without tentacles. 

 20. Chaetostomus gymnorhynchus. 

 Aucistrus gymnorhjTichus, Kncr, Hypostom. p. 275. 

 D. 1/7. A. 5. 

 Head much depressed, occipital and michal regions without any 

 prominence ; the length of the head is one-third of the total (with- 

 out caudal). Snout broad, much depressed, granidated above, wdth 

 a broad soft-skinned margin in its entire circumference ; tentacles 

 none. The chameter of the eye is two-fifths of the width of the 

 interorbital space. Interopcrcidum with thirteen or fourteen ciirved 

 non-flexible spines. Thorax and belly entirely naked. Dorsal fin 

 higher than long ; caudal vertically tnmcated. Scutes of the body 

 with minute spines, not keeled. Brownish. (Kner.) 

 Puerto Cabello. 



21. Chaetostomus nudiceps. 



HjT)ostomus nudiceps, 3Iull. ^- Trosch. in Schumb. Reis. Brit. Guimi. 

 ill. p. G31. 



D. 1/7. A. 5. 



Head much depressed, occipital and nuchal regions without any 

 prominence ; snout covered with soft skin nearly to the eyes ; tenta- 

 cles none. The pectoral spine extends beyond the base of the ventrals. 

 {M. ^ T.) 



British Guiana. 



22. Chaetostomus erinaceus. 

 Hyj)ostomu3 erinaceus, Ctiv. <|- Val. xv. p. 510. 



D. 8. A. 3. P. 1/5. 



Body short, broad, and depressed ; extremity of the snout naked ; 

 interopercidum with a bundle of about twenty setiform spines. Scutes 

 of the body rough, not keeled. ( Vul.) 



ChUe. 



^. Dorsal fin nine- or ten-rayed. 

 * Snout with tentacles. 



23. Chaetostomus dolichopterus. 

 Aucistrus dolichopterus, Kner, Hypostom. p. 274. taf. 3. fig. 1. 

 D.^, A. 5. 



Head much depressed, occipital and nuchal regions without any 

 prominence ; the length of the head is somewhat more than one-third 

 of the total (without caudal). Snout broad, much depressed, covered 

 with soft skin and provided with many tentacles in males, whilst a 

 great portion of its upper surface is granulated in females, only the 

 margin bearing some tentacles. Eye of moderate size, its diameter 

 being two- fifths or one-third of the width of the interorbital space. 

 Intcropcrculum with from six to nine cui'vcd non-flexible spines. 



