30 ME. G. A. BOtJLEXGEE OX FISHES 



35. Plecostomus teknetzi. (Plate V.) 

 Plecoslomus ternetzi, Bouleuger, P. Z. S. 1895, p. 525. 



Head as long as broad, 3 times in total length, with three very obtuse keels ; snout 

 rounded, entirely granulated ; diameter of eye 7 times in length of head, 4 times in 

 length of snout, 1\ times in interorbital width ; barbel as long as diameter of eye ; 

 44 teeth on each side in the upper jaw, and about as many in the lower jaw ; inter- 

 operculum with very small spines. Sides of throat, thorax, and middle of belly covered 

 with small shields. Dorsal I 7 ; first ray as long as head, reaching adipose fin. 

 Pectoral spine as long as head, strong, with small curved spines. Ventral I 5, first 

 ray a little shorter than head. Anal I 4. Lower caudal ray very long, a little longer 

 than head, twice as long as upper. Depth of caudal peduncle 2^ in distance between 

 anal and caudal fins. Posthumeral keel very obtuse and short, not extending beyond 

 base of ventral. Scutes on body rough and spinulose, but not keeled; lat. 1. 25; 14 

 scutes between anal and caudal fins. Uniform olive above, white beneath. 



Total length 240 millim. 



A single specimen from Paraguay. 



This species appears to be nearest allied to P. Jrancisci, Lutk., which is only known 

 to me from the description. 



36. Plecostomus vekmiculaeis, Eigenm. 

 Paraguay. 



37. Plecostomus cochliodon, Kner. 

 Paraguay. 



38. CiiiETOSTOiius gigas. (Plate VI.). 

 Cluetustomus gigas, Boulenger, P. Z. S. 1895, p. 526. 



15 upper and 19 lower teeth on each side. Depth of body 4J times in total length, 

 length of head 2f times. Head a little longer than broad, entirely rough with small 

 spines; snout broadly rounded; diameter of eye 11 times in length of head, 4f times 

 in interorbital width, 6 times in length of snout ; anterior border of orbit with enlarged 

 spinules ; no postorbital groove ; erectile prseopercular spines very strong, the longest 

 2\ diameter of orbit ; barbel a little longer than diameter of orbit. Throat and belly 

 studded with small rough shields. Dorsal I 10; all the rays rough with spinules, the 

 first measuring f length of head. Pectoral spine as long as head, covered with small 

 spines, the longest of which are hooked and nearly equal diameter of orbit. Ventral I 5, 

 as long as first dorsal ray. Anal I 5. Caudal obliquely truncate, lower ray longest. 

 Shields on body rough with ridges of strong spinules, 25 in a longitudinal series. 

 Brown, densely covered all over with round black spots. 



Total length 530 millim. 



A single specimen from Paraguay. 



