93. PLECOSTOMUS. 231 



The species may be subdivided thus : — 

 a. Teeth in both jaws very fine, numerous. 



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



stomus, Blkr., p. 231. 

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

 dually longer posteriorly : Pseudancisirus, 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. Syst. Nat. i. p. 508 ; Bl. taf. 374 ; Bl. Schn. 



p. 124. 

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



tab. 3. figs. 1 '& 2. 

 Loricaria flava, Shaw, Zool. v. p. 38. pi. 101. 

 Hypostomus plecostomus, Cuv. ty Vol. xv. p. 489; Kner, Hypostom. 



p. 263. 

 Plecostomus bicirrhosus, 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 papillae*. Interoperculum with minute, very 

 short setiform spines. Thorax and belly nearly entirely covered 

 with minute 1 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 brown dots ; 

 bodj/ and fi^s with larger round spots, which are most distinct on the 

 abdominal surface. 



Brazil ; 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-grown. Cayenne. 



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



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



i. Adult. Purchased of Mr. Stevens. 



2. Plecostomus panthernras. 

 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 (with the 



* The teeth vary in number ; I count from sixteen to twenty-six in each man 

 dible and intermaxillary in specimens from the same locality. 



