i 9 4i CATALOGUE OF FISHES OF TORTUGAS 2 ™ 



pt. 3, 1898, p. 2280) called attention to the possibility that "species" of the former 

 may include males only, those of the latter the corresponding females. Meek and 

 Hildebrand (Field Mus. Nat. Hist., Zool. Ser., vol. 15, pt. 3, 1928, p. 900) con- 

 cluded that Gnathypops scops is indeed the female of Opisthognathus ommatum , 

 and their recognition of the single sexually dimorphic species Opisthognathus 

 scops (Jenkins and Evermann) lends strength to the hypothesis. The paucity of 

 material available for study makes it impossible to determine, however, how 

 generally sexual dimorphism occurs. Even the readily accessible material at 

 Tortugas does not answer the question, since no species seem to breed there dur- 

 ing the summer. 



Still, one observation makes it clear that the difference between the two genera 

 is overemphasized: Opisthognathus lonchurus Jordan and Gilbert and Gnathy- 

 pops mystacinus Jordan are surely the same species. For the present, then, though 

 for a somewhat different reason, I join Meek and Hildebrand in regarding 

 Gnathypops as a synonym of Opisthognathus. W. H. L. 



Opisthognathus lonchurus Jordan and Gilbert 



Opisthognathus lonchurus Jordan and Gilbert, Proc. U. S. Nat. Mus., vol. 5, 1882 (1883), 



p. 290 — Snapper Banks off Pensacola, Florida. 

 Gnathypops mystacinus Jordan, Proc. U. S. Nat. Mus., vol. 7, 1884, p. 37 — Snapper Banks 



off Pensacola, Florida. 



Of what seems to be this species I have 1 small specimen, taken in 40 to 50 

 fathoms, south of Tortugas. It is 29 mm. long to caudal base. 



Eye very large, before which the profile falls very abruptly, making the snout 

 very short. Head 10 mm.; eye 4.0 mm.; snout 1.0 mm. D. XI,i2 1 /2; A. Ill, i2 l / 2 ; 

 P. 19. Scales very small and hard to count, about 85 transverse series between 

 upper angle of gill opening and base of caudal fin, 17 longitudinal series between 

 last rays of dorsal and anal; about 55 pores in lateral line; upper jaw with 

 canines of irregular sizes, in a single row except anteriorly, where in an inner 

 row are 3 or 4 on either side of the symphysis; teeth arranged similarly in lower 

 jaw, except that in the inner row are 6 or 7 on either side of mid-line; 2 teeth on 

 vomer, one much stronger than the other. 



In life pale olivaceous above and white below; dorsal fin slightly darker toward 

 the margin, and anal fin with an orange spot between 7th and 9th rays. 



Jordan and Gilbert's and Jordan's species, cited above, were based on material 

 recovered in rather poor condition from the stomachs of Lutianus aya, caught in 

 deep water. The first is said to have the fin formulas D. 25; A. 15; 67 rows of 

 scales in transverse series; and 5 large teeth on the vomer; the second, D. 23 or 

 24 (X,i4); A. II, 11; about 54 tubes in lateral line; 100 scales between gill open- 

 ing and caudal; vomerine teeth 4. It appears, however, from re-examination of 

 type material, that this is not entirely accurate. Type and cotype of Opisthog- 

 nathus lonchurus have D. XI,i2^4; the cotype A. Ill, 12, the type 12 anal rays 

 only, the spines having been lost in the process of digestion. The fin formulas in 

 the type of Gnathypops mystacinus are also D. Xl,i2Y 2 ; A. Ill, 12. Type and co- 

 type of the first have respectively 7 and 3 vomerine teeth; the type of the second 



