i94i CATALOGUE OF FISHES OF TORTUGAS 1T y 



food obtained, which seemed to show that the schools from different places have 

 different feeding grounds. He pointed out, furthermore, that the food of the gray 

 snapper and the schoolmaster is sufficiently different to show that they frequent 

 entirely different feeding grounds. 



In Carnegie Institution of Washington Year Boo\ No. 24 (1925, p. 232), 

 Longley, Schmitt, and Taylor reported at greater length on the conspicuous dif- 

 ferences that appeared in the stomach contents of fish from the different colonies 

 of gray snappers studied. The claim is made that it would be possible to deter- 

 mine, from an average sample of 10, from which of seven different sites the fish 

 in question had come. The differences in the food of the gray snapper and the 

 schoolmaster, also, are discussed in detail. 



Dr. Longley carried on extensive experiments designed to provide further 

 information 1 concerning the gray snapper's ability to discriminate colors. These 

 experiments were reported upon in Carnegie Institution of Washington Year 

 Boot{ Nos. 22 (1923, pp. 161-163), 23 (1924, p. 193), 24 (1925, p. 228), and 29 

 (1930, p. 337). A brief review follows: 



The plain-colored hardhead, Hepsetia stipes (listed as Atherina laticeps in the 

 reports cited), was used as the food by means of which the color discrimination 

 of the snappers was tested. The minnows, preserved in a weak solution of for- 

 malin in the earlier experiments, were painted in two color patterns with silver 

 nitrate. One pattern consisted of a dark lateral stripe, extending from snout to 

 tail, and the other consisted of two dark crossbars. The snappers (colonies under 

 near-by piers) preferred the striped minnows, but did eat the barred ones too. 



Then an attempt was made to make those of one pattern distasteful to the 

 snappers by sewing into the mouth pieces of the tentacles of the medusa, 

 Cassionea. After a time the colony of fish that had been fed with striped fish 

 (for which they originally had shown preference) made distasteful with the 

 medusa tentacles came to show a marked preference for banded fish. This prefer- 

 ence was maintained afterward even though the medusa tentacles were omitted. 

 Another colony of snappers similarly was taught to avoid banded fish. 



The experiments were continued through three summers. No doubt remained 

 that the gray snapper can distinguish color patterns, and that it can be taught to 

 avoid certain ones, though the rate of learning seemed rather slow. 



Dr. Longley was not satisfied, however, with the results of the experiments 

 performed. Accordingly he made further investigations during the summer of 

 1929, in which he used fresh as well as preserved Hepsetia stipes. The earlier 

 experiments were made with colonies of snappers living under one or another 

 of the wharves of Loggerhead and Garden keys. The membership of these 

 groups, it was learned, varied from day to day. In the new experiments 25 gray 

 snappers of an average length of about 10 inches were confined alone in a land- 

 locked part of the moat about Fort Jefferson. These fish soon learned to dis- 

 tinguish formalin-preserved from fresh minnows. Dr. Longley concluded: "The 

 snappers' power of readjustment is great, and fresh fishes, even when they bear 



1 The ability of the gray snapper to distinguish colors had already been investigated to 

 some extent by Jacob Reighard (Carnegie Inst. Wash. Pub. 103, 190(8, p. 257). 



