03. PLECOSTOMUS. 233 



covered with minute scutes. The lenc/th of the base of the dorsal Jin 

 is more than its distance from the second Jin. There are eight scutes 

 between the two tins. Caudal fin obliquely emarginate. The pectoral 

 spine extends to the second third of the length of the ventral fin, and 

 has its extremitj' covered with very short spines. Sixteen scutes be- 

 tween anal and caudal ; the lateral scutes of the bodj' with slightly 

 serrated keels. Head, back, and fins with numerous broAvn dots ; 

 three or four irregular series of dots in each interracUal space of the 

 dorsal fin ; caudal fin nearly uniform blackish. 

 Erazil, 



a. Adult. Rio Grande. Purchased of Mr. Stevens. 



5. Plecostomus punctatus. 



PHypostouius punctatuS; Cuv. ^- Val. xv. p. 493. 



D. 1/7. A. 5. P. 1/6. V. 1/5. L. lat. 31. 



Head rather depressed, its length being one-foui'th of the total 

 (withoiit caudal) ; no ridge between eye and nostril ; superciliary 

 edge not elevated ; occiput with a slight longitudinal elevation along 

 its middle, and somewhat produced backwards ; nuchal scutes incon- 

 spicuously bicarinate. The middle of the extremity of the snoiit is 

 naked ; labial fold of moderate Avidth, not notched behind, covered 

 with minute papillte. Interoperculum without any spines. The 

 entire lower side of the head, thorax, and belly covered with minute 

 scutes. The length of the base of the dorsal is less than its distance 

 from the second Jin; there are nine scutes between the two fins. 

 Caudal fin obliquely emarginate. The pectoral spine extends some- 

 what b(!yond the base of the ventral, and has its hinder portion 

 covered with .small ciu'ved spines. Sixteen scutes between anal and 

 caudal ; the lateral scutes of the body with indistinct keels, each keel 

 terminating in a bundle of veiy small spines. Head, back, and fins 

 Avitli numerous brown dots ; they are arranged in two series betvveen 

 evei-j' pair of the dorsal rays, and in a single series between the 

 caudal rays. 



Brazil. 



</. Adult. Brazil? 



''. Adult : stuffed. South America. 



6. Plecostomus emarginatus. 



Cuv. 4- Val. XV. p. 500. 



D. 1/7. A. 1/4. P. 1/0. 

 Body and tail rather elongate. The pectoral spines extend scarcelj- 

 to the base of the ventral ; scutes \-eiT slightly keeled. The occipital 

 shield has an obtuse prominence, and instead of being produced be- 

 hind, it is emarginate. Two series of spots in each interradial space 

 of the dorsal fin. (!'((/.) 

 Brazil ? 



