238 PAPERS FROM TORTUGAS LABORATORY vol. xxxiv 



Family OPISTHOGNATHIDAE. Jawfishes 



As a convenience to those using this monograph, a key to the genera and 

 species is offered, which seems especially desirable, as two previously unknown 

 species have recently been described. S. F. H. 



Key to the Genera and Species 



a. Dorsal spines flexible; cheeks and opercles naked; caudal rounded or 

 at most only slightly pointed; gill rakers 35 or fewer on lower limb 



of first arch Opisthognathus 



b. Dorsal and anal fins short, the former with XI, 12 and the latter 

 with III,i2 rays; body plain olivaceous in life, light brown in 



preservative lonchurus 



bb. Dorsal and anal fins longer, with more than 23 spines and di- 

 vided rays in the dorsal, and more than a total of 15 in the anal 

 c. Caudal fin broadly rounded; gill rakers 23 or fewer on lower 

 limb of first arch; body and dorsal fin variously spotted with 

 dark or black blotches; two pale spots on base of caudal fin, 

 one above and one below middle line 

 d. Maxillary with a supplemental bone; eye very large, 

 about 2.5 in head; dark blotches on back not extending 

 on base of dorsal fin; dorsal with a black spot high up 



on fin, between spines 7 and 9 or 10 fasciatum 



dd. Maxillary without a separate supplemental bone; eye 

 smaller, 3 or more in head 



e. Scales small, about 90 to roo in lateral series; dark 

 blotches on back and along middle of side large, 

 those on back extending distinctly on base of dorsal 

 fin; a prominent black spot near base on dorsal 



between spines 6 and 9 or 10 maxillosus 



ee. Scales larger, about 55 in lateral series; blotches on 



body smaller and less distinct; a prominent dark 



spot on dorsal between spines 2 and 4 or 5 . . . whitehurstii 



cc. Caudal sharply rounded to somewhat pointed in adult; gill 



rakers about 33 on lower limb of first arch; scales very small, 



about 115 in lateral series; body light brown in preservative, 



golden brown in life; no spots on body or fins; dorsal, and 



sometimes anal, with black margins, blue in life aurifrons 



aa. Dorsal spines stiff, pungent; cheeks and opercles scaled; caudal 

 lanceolate; D. XI, 16; A. Ill, 16; scales in lateral series about 63; gill 

 rakers about 39 on lower limb of first arch . . . Lonchopisthus micrognathus 



Opisthognathus Cuvier 



Opisthognathus Cuvier, Regne animal, 1st ed., 1817, p. 252 (O. sonnerati Cuvier). 

 Gnathypops Gill, Proc. Acad. Nat. Sci. Philadelphia, vol. 14, 1862, p. 241 {Opisthognathus 

 maxillosus Poey). 



The relation of species of Opisthognathus and Gnathypops has been for a long 

 time, and still is, puzzling. Jordan and Evermann (Bull. U. S. Nat. Mus., No. 47, 



