212 MR. C. TATE REGAN ON THE 



11. Plecostomus cordov^. (Plate IX. fig. 3.) 

 Plecostomus cordovae Giinth. Ann. Mag. Nat. Hist. (5) vi. 1880, p. 11. 



Depth of body nearly 8 times in the total length, length of head of times. Depth 

 of head 2| times in its length, breadth of head 1^ times, length of snout If times, 

 diameter of eye 10 times, interorbital width 3 times. Length of mandibular ramus 

 1J times in the interorbital width. Snout broad, rounded ; supraorbital edges 

 slightly raised ; supraoccipital with low median ridge ; temporal plates carinate. 

 Scutes spinulose, those of the upper series and the anterior of the second series 

 carinate, 30 in a longitudinal series, 10 between dorsal and adipose fin, 17 between 

 anal and caudal. Supraoccipital bordered posteriorly by a median scute and by one 

 on each side. Lower surface of head and abdomen almost completely covered with 

 small granular scales. D. I 7, the first ray nearly as long as the head, the last half 

 as long ; length of base of dorsal less than its distance from the adipose fin. A. I 4. 

 Pectoral spine extending to base of ventral. Caudal emarginate, the inner rays equal 

 to f- the length of the outer, which are as long as the head. Caudal peduncle 

 4^ times as long as deep. Head and body with dark spots, fins with irregular dark 

 cross-bars. 



Total length 220 mm. 



One specimen : Cordova, Argentine Republic. 



12. Plecostomus bokellii. (Plate IX. fig. 2.) 



Plecostomus borellii Bouleng. Boll. Mus. Torino, xii. 1897, no. 279, p. 2. 



Depth of body nearly 7 times in the total length, length of head of- times. Depth 

 of head If times in its length, breadth of head once, length of snout If times, 

 diameter of eye 7h times, interorbital width 3 times. Length of mandibular ramus 

 1^ times in the interorbital width. Snout broad, rounded ; supraorbital margins not 

 raised; supraoccipital with low median ridge; temporal plates weakly carinate. 

 Scutes spinulose, the anterior of the two upper series weakly carinate, 28 in a 

 longitudinal series, 9 between dorsal and adipose fin, 15 between anal and caudal. 

 Supraoccipital entirely bordered posteriorly by a single scute. Lower surface of head 

 and abdomen, in the adult, almost completely covered with small granular scales. 

 D. I 7, the first ray f the length of head, the last f as long ; length of base of dorsal 

 a little less than its distance from the adipose fin. A. I 4. Pectoral spine not 

 extending beyond base of ventral. Caudal slightly emarginate, the outer rays as long 

 as the head, the inner f as long. Caudal peduncle 3| times as long as deep. Blackish 

 spots on the dorsal fin. 



Total length ] 80 mm. 



One specimen : Bolivia. 



