1941 CATALOGUE OF FISHES OF TORTUGAS 2 22 



nets. It has been observed a few feet seaward from low-tide mark on Loggerhead 

 Key and on the flats and banks in the deep hole east of Bird Key, and full-grown 

 specimens most commonly on patches of gravel washed free of fine sand near the 

 bases of coral stacks, in the deeper holes on the northern part of Loggerhead 

 bank, and on parts of the comparatively barren eastern half of the bank. 



The burrows, which it was not actually seen excavating, are irregular holes 

 under or between coral fragments. When undisturbed the fish "float" above their 

 retreats. When alarmed they sink and assume a horizontal position, or with the 

 head slightly inclined downward, ready to dart out of sight with almost in- 

 credible speed on the closer approach of danger. They are not readily driven out 

 of their burrows by stirring up the sand about them, nor do they attempt to 

 escape when copper sulphate is injected. They are, indeed, collected with con- 

 siderable difficulty, except with dynamite. 



Two adult fish commonly live together, and often smaller ones attach them- 

 selves to the pair. Seven young, of two sizes, were seen once, and 5 to 7 of uni- 

 form size were repeatedly seen sharing the refuge of their elders. 



The young, at the length of 25 mm., have the caudal fin slightly forked, therein 

 differing greatly from the adult, in which this fin is lanceolate. W. H. L. 



Hildebrand and Cable (Bull. U. S. Bur. Fish., vol. 48, no. 24, 1938, pp. 548-574) 

 and Hildebrand (Field Mus. Nat. Hist., Zool. Ser., vol. 22, 1938, pp. 345, 348) 

 have described the development of the caudal fin in several species of Eleotridae 

 and Gobiidae as similar to that in Ioglossus calliurus. It would appear that a 

 concave or truncated caudal in the juveniles of those species that in adult life 

 have a rounded or lanceolate caudal is usual among gobies. This mode of de- 

 velopment is opposite to that of many other groups of fish. 



The following concerning color was compiled from Dr. Longley's notes: 

 General color olivaceous; a bluish stripe, half the width of pupil, extending from 

 eye to upper angle of gill cleft; several small dots of blue on opercle; frilled 

 membrane from tip of chin to isthmus blue and orange. Both dorsals with con- 

 spicuous dark margins, the rest of fins pale olivaceous like the body, except for 

 very faint blue longitudinal lines; ventrals and lower two-thirds of caudal rosy, 

 upper third of caudal like the body. 



A "large specimen" is described as having the margin of first dorsal rosy, and 

 anal and lower half of caudal also rosy. In still another specimen the dorsal was 

 described as having a black margin only on the last 13 "spines," presumably 

 meaning the last 13 rays of the second dorsal. In this specimen the lower half of 

 the caudal and the entire anal were ruddy. 



The 5 preserved specimens at hand, 40 to 103 mm. long, are now entirely color- 

 less, except for a prominent black margin extending the full length on both 

 dorsals in the largest and smallest specimens, present only on the posterior half 

 in a 51-mm. fish, and entirely missing in one 83 mm. long. 



The following enumerations based on 2 specimens are recorded in Dr. Long- 

 ley's notes: D. VI-I,22, VI-1,23; A. 1,22, 1,22. I have counted in 2 specimens, 

 D. VI-L22, VI-L23; A. 1,21,1,22. 



The specimens have a low dermal crest, precisely like Coryphopterus glauco- 



