!86 PAPERS FROM TORTUGAS LABORATORY vol. xxxiv 



resting on the bottom entered the water, or, again, about the bases and in the 

 crannies of the concrete foundations of the old coal sheds. 



On one occasion 3 adult and 1 partly grown one, and several young A. saxatilis 

 were under continuous observation side by side for several hours. On the sloping 

 beach rock where they were, two plant associations might be readily distin- 

 guished. In an upper zone, nearer the shore, Cladophora and Ectocarpus were 

 dominant; in a lower zone Laurencia predominated. Seaward from the rock was 

 a strip of bare white sand. While watched, not one A. taunts ventured into the 

 upper zone, but freely fed from the bottom, browsing greedily as A. saxatilis 

 never does; the latter, on the contrary, rose readily from the bottom, which 

 A. taunts hugged closely. In conformity with the difference in instinct exhib- 

 ited, A. taurus rarely swims over an obstruction under which it is able to pass, 

 whereas A. saxatilis at times swims freely at the surface. W. H. L. 



The following notes on color were extracted from Dr. Longley's field data, 

 based on under-water observations: It is a dual-colored fish, being obliteratively 

 shaded with sepia and bands of cream color or vice versa. It has a light line ex- 

 tending from the gill opening to the occiput, where it meets its fellow of the 

 other side. The first dark crossbar is broader dorsally than ventrally and is 

 margined on both sides with pale color. The dark bars become paler on the 

 lower part of the side, and do not continue ventrally. Pectorals transparent; other 

 fins more or less ashy. 



The collection contains no specimens. Aside from the differences in color 

 mentioned, I judge from an under-water picture that A. taurus has a less deeply 

 forked caudal than A. saxatilis. Jordan and Thompson (Bull. U. S. Bur. Fish., 

 vol. 24, 1904 (1905), p. 245) stated, "Dusky bands fainter than in Abudefduf 

 marginatus [— saxatilis), twice as broad as the interspaces and growing fainter 

 below; a faint band on caudal peduncle, making 6 dark bands in all; fins all 

 dusky. This species is distinguished from A. marginatus by the larger scales, the 

 much broader, fainter crossbands, of which 6 rather than 5 are distinct, and the 

 rather broader preorbital." 



West Indies to Florida. S. F. H. 



Stegastes chrysurus (Cuvier and Valenciennes) 



Glyphisodon chrysurus Cuvier and Valenciennes, Hist. nat. poiss., vol. 5, 1830, p. 476 — 



St. Thomas. 

 Pomaccntrus dcnegatus Poey, Memorias, vol. 2, i860, p. 190 — Cuba. 

 Pomacentrus niveatus Poey, Enumeratio, 1875, p. 102 — Havana. 



Common, although more than 3 or 4 are not often seen together. It haunts the 

 coral stacks, away from which it scarcely ventures. 



It browses on the delicate algae covering dead coral surfaces. 



A single fish may in a few moments vary in color from faded russet to deep 

 brown, almost black, rich and lustrous. The tail of the adult is yellow in all 

 phases, but in the young, approximately 60 mm. long, it is colorless. The ground 

 color in the young {Pomacentrus niveatus Poey) is paler and bluer than in the 

 adult, and is profusely dotted (body and fins) with more metallic blue. These 



