93. PLECOSTOMFS. 231 



The species may be subdivided thus : — 

 a. Teeth in both jaws very fine, numeroua. 



• Margin of the snout granulated, without bristles : Pleco- 



stoDiKS, Blkr., p. 281. 

 ** Margin of the snout with short bristles, which become gra- 

 dually longer posteriorly : Pseiidaucuitrus, Blkr., p. 237. 

 /3. Both jaws with small teeth, few in number, much dilated at the 

 crown: Cochliodon, Heck., p. 238. 



a. Teeth in both jaws very fine, numerous. 



• Margin of the snout granulated, without bristles. 



1. Plecostomus bicirrhosus. 



Loricaria plecostomus, L, Si/st. Nat. i. p. 508 ; £1. taf. 374 ; £1. Sch)i. 



p. 124. 

 Plecostomus, Gronov. Mm. Ichth. i. p. 24. no. 67, and Zoophyl. no. 394. 



tab. 3. figs. 1 & 2. 

 Ijoricaria fiava, Shaw, Zool. v. p. 38. pi. 101. 

 Hj-postonius plecostomus, Cuv. i^ Val. xv. p. 489 ; Kner, Hypostom. 



p. 203. 

 Plecostomus biciniiosus, Gronov. Syst. ed. Gray, p. 158. 



D. 1/7. A. 5. P. 1/6. V. 1/5. L. lat. 26. 



Head not much depressed, its length being two-sevenths of the 

 total (without caudal) ; a rather prominent ridge runs from the eye 

 to below the nostril, the side of the head below the ridge being 

 slightly concave. Occiput with a rather elevated ridge, scutes of the 

 nape bicarinate. Labial fold of moderate width, not notched behind, 

 covered with minute papilla)*. Interoperculum with minute, very 

 short setiform spines. Thorax and belly nearly entirely covered 

 with minute scutes. The lower caudal lobe is considerably stronger 

 than the upper ; the upper and lower caudal rays are prolonged, and 

 subequal in length. Head with numerous closely-set browu dots ; 

 body and fins with larger round spots, which are most distinct on the 

 abdominal surface. 



BrazU ; Surinam ; Venezuela. 



a-c. Adult and half-grown. British Guiana. 



d. Adult : stuffed. British Guiana. 



e. Half-grown. Dutch Guiana. Purchased of Mr. Frank. 

 /. Half-groAvn. Cayenne. 



g. Young. Para. Presented by R. Graham, Esq. 



h. Half-grown : bad state. Purchased of Mr. Bartlett. 



». Adult. Purchased of Mr. Stevens. 



2. Plecostomus pantherinas. 



Kner, Hypostom. p. 267. 



D. 1/7. A. 5. P. 1/6. L. lat. 24-25. 

 The length of the head is only one-third of the total (^\-ith the 



* The teeth van in munber ; I count from sixteen to twcntv-six in eacli m.in- 

 dible and iutcrmaxillarj in specimens from the same locality. 



