46 ACAKTHOPTEETGII. 



C. Opercular flap extending to or bej'ond the vertical from origin of dorsal; 48-60 scales in a 

 longitudinal series. 

 ]. 17-19 gill-rakers, including 2 to 4 rndimcnts, on the lower part of 

 antei'ior arch ; 5 to tJJr scales between middle of second dorsal and 

 lateral line. 

 Third dorsal spine longer than fourth ; second anal spine about 1 the 



length of the fish (in specimens of 300 mm.) ........ 7. robalUo. 



Third and fourth dorsal spines snbequal ; second anal spine al)ont \ the 



length of the tish (in specimens of nearly .'300 mm. ) 8. ensifcrus. 



.2. 13-15 gill-rahers, including 2 or 3 rudiments, on the lower pai't of 

 anterior arch; 7 to Si scales bctwten niiddle of second dorsal aud 

 lateral line. 

 Third anal s})iuc ^|-^ as long as second, which is j~l the length of the 



hsli (in specimens of 210-2G0 mm.) 9. armatiif:. 



Third anal spine ;t as long as second, which is \ the length of the fish 



(in a specimen of 170 mm.) 10. altus. 



Third anal spine neai'ly as long as second, which is less than ! the length 



of the fish (in a specimen of 260 mm.) 11. umonensis. 



The length of the fish is measured from the tip of the snout to the base of the caudal 

 fin, that of the head from the tip of the snout to the extremity of the opercular flap, 

 which appears to be a true prolongation of the suboperculum and distinct from the 

 branchiostegal membrane ; the projecting lower jaw is not included in either case. 

 The scales are counted in a longitudinal series abo\'e the lateral line from the supra- 

 clavicle to the base of the caudal fin, not including the scales covering the basal part 

 of the fin. 



In using the descriptions the size of the specimens described must be taken into 

 account. Young specimens have the head proportionately longer, eye larger, snout 

 and maxillary shorter and vertical fins more developed than the adults. 



In the case of C. nitjresceiis tlie second anal spine is described as -f~\ the length of the 

 fish in specimens of 150-300 mm. in total length ; i. e., -J- in the smallest example and -} 

 in the largest. C. vtHlecimalis also is described as having the second anal spine y—|- the 

 length of the fish, but this is in specimens of :^30-G00 mm. in total length, the spine 

 being longer in this species than in C. nigrescens, when examples of the same size are 

 compared. 



1. Centropomus pectinatiis. 



Criifroponms imdecimarm (part.), (.'uv. & Val. Hist. Nat. Poiss. ii. p. 102 (1828) '; Ciiinth. Cat. 



Fish. 1. p. 70 (1859) \ 

 Crn/ro/jonm-s 'pecthidiiis, Poey, Mem. Cuba, ii. p. 121 (1860) ', and Repert. ii. p. 280 (1868) ' ; 



Vaill. & l^DC. i\]i.ss. Sc. Mex., Poiss. p. 25 (1871) " ; Bouleug. Cat. Fish. i. p. 368 (1895) '' ; 



.lord. & j'ivcrm. Pull. U.S. Nat. J\ius. .xlvii. 1896, p. 1122''. 

 Cadrujioiuus jiedtiiiacula, Vocy, Mem. Cuba, ii. p. 122 (1860j ", aud Repert. ii. p. 280 (1868)°; 



