43 o Memoir Sears Foundation for Marine Research 



Castelnau, x\nim. Nouv. Rares Amer. Sud, Poiss., 1855: 57, pi. 28, fig. 3 (based on material of Valen- 

 ciennes). 

 Pristigaster cayana Myers, Copeia, 1956: 64 (nomencl., early synon. corrected). 



Negative Reference: 



Prisligasler martii Fowler, Bull. Amer. Mus. nat. Hist., yo (i), 1936: 179, fig. 72 (synon. in part incorrect; 

 descr. after P. dolloi Boulenger, which is not this species). 



Genus Odontognathus Lacepede 1800 



Odontognathus Lacepede, Hist. Nat. Poiss., 2, 1800: 220; type species by monotypy, Odontognathus mucronatus 

 Lacepfede. 



Generic Synonym: 



Gnathobolus Bloch and Schneider, Syst. Ichthyol., 1801: 556; type species by monot)py, Odontognathus mucro- 

 natus Lacepede. 



Characters. Body strongly compressed; the dorsal outline more or less concave 

 over head, the ventral outline rather strongly convex anteriorly. Bony scutes on sharp 

 keel of chest and abdomen, the outer margin of the posterior scutes more or less 

 denticulate. Mouth strongly oblique to nearly vertical, with strongly projecting 

 lower jaw. Maxillary greatly produced in large examples; maxillary and premaxillary 

 separated by a toothless membranous section, forming a continuous (uninterrupted) 

 margin with maxillary and premaxillary. Teeth small to minute, present on both jaws, 

 palatines, pterygoids, and tongue, but wanting on vomer. Gill rakers not numerous, 

 about 19-25 on lower limb of first arch. Dorsal fin rather feebly developed, with about 

 10—14 rays. Anal fin long, with about 52—80 rays, beginning far in advance of dorsal 

 fin, generally well in advance of midlength of SL. Pelvic fins wanting. Pectoral 

 fins generally longer than head. 



Remarks. The species of this genus have greatly compressed bodies, a concavity 

 over the head, a membranous section between the maxillary and premaxillary that 

 forms a continuous margin with the two elements it separates, a very oblique to nearly 

 vertical mouth, and a very long anal fin. Several of the posterior ventral scutes generally 

 are denticulate. 



Range. Known from both coasts of Panama, on the Atlantic side southward to 

 Guiana. 



Key to Species 



I a. Depth of body 4.65 in SL; anal fin with 79 or 80 rays (71—82 by earlier descrip- 

 tions); dorsal fin over middle of anal, its origin about twice as far from poste- 

 rior margin of eye as from base of caudal. mucronatus Lacepede 1800, p. 431. 



lb. Depth of body 3.5—4.25 in SL in adults; anal fin with only 52-60 rays; dorsal 

 fin ending over middle of anal, its origin nearly twice as far from margin of snout 

 as from base of caudal. compressus Meek and Hildebrand 1923, p. 433. 



