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Show 1 906.] * FRESH-WATER FISHES OF TRINIDAD. 381 2. Two dorsal fins. a. Anterior dorsal of 4 spines. a. Jaws with bands of small pointed teeth. 28. Agonostomus monticola. (3. Jaws with minute ciliiform teeth * ; anal fin usually with III 8 rays; 32 to 36 scales in a longitudinal series. Second dorsal with a series of small scales behind each ray, otherwise naked 29. Mugil brasiliensis. Second dorsal covered with small scales 30. 31. trichodon. b. Anterior dorsal of 7 or 8 spines; anal with 3 spines, the second and third strong f. 65-75 scales in a longitudinal series; second and third anal spines subequal 31. Centropomus undecimalis. 50-60 scales in a longitudinal series; second anal spine considerably longer than third 32. C. ensifcrus. c. Anterior dorsal of 6 or 7 slender flexible spines; anal with a single feeble spine %. Vomer toothed ; lower jaw projecting; scales small. 37. Philypnus dormitator. Vomer toothless ; jaws equal anteriorly; scales rather large. 38. Dormitator maculatus. B. Ventrals united to form a disc. 1. Jaws with bands of small pointed teeth and an outer series of larger teeth. 32 scales in a longitudinal series 39. Gobius fasciatus. 60-75 scales in a longitudinal series 40. Chonop'horus banana. 2. Teeth in the jaws in a single series 41. Mvorthodus breviceps. * Although only 31. brasiliensis and 31. trichodon have been actually recorded from Trinidad, there can be but little doubt that all the species of 31ugil which occur on the Atlantic coasts of America are to be obtained there. These may be distinguished as follows :- I. Second dorsal naked except for a series of small scales behind each ray; anal with III 8 rays (rarely III 7 or III 9). 38 to 42 scales in a longitudinal series cephalus L. 32 to 36 scales in a longitudinal series brasiliensis Ag. II. Second dorsal covered with small scales. A. Anal with III 9 rays (rarely III 8). 42 to 45 scales in a longitudinal series incilis Hancock. 36 to 39 scales in a longitudinal series curema C. & V. B. Anal with III 8 rays (rarely III 7 or III 9); 32 to 36 scales in a longitudinal series trichodon Poey. f Probably all the Atlantic species of Centropomus occur in the rivers of Trinidad. They may be distinguished thus :- I. Anal with III 7 rays, the second and third spines subequal. pectinatus Voej. II. Anal with III 6 rays. A. Second and third anal spines subequal; 65 to 75 scales in a longitudinal series undecimalis Bl. B. Second anal spine longer than third. 75 to 90 scales in a longitudinal series parallelus Poey. 50 to 60 scales in a longitudinal series ensiferus Poey. X Allied to Philypnus dormitator and certainly to be found in the rivers of Trinidad are two species which may be distinguished thus :- Vomer toothless ; lower jaw projecting ; scales small. Dorsal with VI, I 8 rays Meotris pisonis G m. Dorsal with VII, I 10 rays E. guavina C. & V. |