i94i CATALOGUE OF FISHES OF TORTUGAS ^3 



of which were caught several times. In one instance a fish smaller than an aver- 

 age adult was in a state of high excitement beneath a coral. In uniform dusky 

 yellow-olive, except for a darker visor, it emerged and, dashing this way and 

 that in broken curves, whirled about a larger individual in just such blue and 

 gold as marks the young. By direct attack another was driven away. Shortly 

 thereafter the fish became quiet and assumed its normal coloration. I believe that 

 this was an unsuccessful attempt of the male to induce the female to enter and 

 lay her eggs. I have also seen the blue-black male, with yellow spread over his 

 dorsal surface only, go into a Strom bus shell with a smaller fish, apparently a 

 female, swim in and out several times while she remained, and then drive her 

 away as she began to feed on eggs already there. 



The eggs are the charge of the male alone. He is in the highest degree in- 

 tolerant of the approach of fish of his own or other species, which he pursues and 

 nips whenever they draw near. Except as his pugnacity may be increased, his 

 behavior during the breeding season seems little changed. He feeds freely while 

 on guard, but is true to his trust and eats no eggs. He keeps his shelter unen- 

 cumbered by material which may fall or float in and interfere with free passage 

 to or from it. One was found removing bits of algae which ground swells washed 

 into the hole it was occupying. When a mass of Sargassum composed of pieces 

 several inches long was thrust in to test its reaction, it worked continuously for 

 5 to 10 minutes clearing the opening, interrupting its labor repeatedly to drive 

 away small Halichoeres. It also carried out sand in its mouth. Repeated trials 

 showed that nest cleaning is a habitual response. 



The stereotyped form of the instinct of guarding the nest may also be readily 

 demonstrated. A Strom bus shell containing eggs was removed only a yard from 

 its original place. Many Halichoeres biuittatus were drawn at once to the spot by 

 the disturbance. The guardian male, greatly excited, kept all fish away from the 

 original site, but paid no attention. whatever to those swarming about the shell in 

 its new location, greedily devouring eggs and larvae. When the shell was placed 

 at a point only 18 inches from its first position, care for it was renewed. This care 

 continued when it was set a yard away for the second time, but the original site 

 exercised a persistent influence on the fish's behavior, and sustained effort was 

 made to preserve both from invasion. A fish picked up with its shell, and carried 

 away as far as 40 feet, may when liberated go straight to the spot from which it 

 came, its sense of direction being excellent, or its acquaintance with the ground 

 about its station detailed. Fish disturbed by such testing of their homing powers 

 may eat their eggs, and eggs in shells exchanged are eaten as a matter of course. 



West Indies to Florida, sometimes straying northward. W. H. L. 



Abudefduf saxatilis (Linnaeus). Sergeant major 



(Plate 24, figure 1) 



Chaetodon saxatilis Linnaeus, Syst. nat., 10th ed., 1758, p. 276 — "India"; ibid., 12th ed., 



1766, p. 466 — Brazil. 

 Chaetodon marginatus Bloch, Naturgesch. ausland. Fische, vol. 3, 1787, p. 98, pi. 207 — 



Martinique (after a drawing by Plumier). 



