574 W. H. LONGLEY 



The study of blue has yielded results that are unsurpassed hi 

 suggestiveness, but it is much more difficult in some respects 

 than other equally important undertakings, and has been neg- 

 lected in proportion. 



This color seems to occur in nature in prominent markings, or 

 as a self-color, upon no fishes which lie close upon the bottom, 

 although Mast's ('14) flounders distinctly developed it under 

 experimental conditions. Similarly, it is wanting upon those 

 living just beneath the surface film, except as there are bluish 

 reflections from the silvery lateral stripe of some of he Esocidae, 

 for example. It appears in a great variety of tints and shades, 

 ranging from the blue-gray of Abudefduf saxatihs and Ocyurus 

 chrysurus through the pale blue of Gnathypops aurifrons and 

 Scarus caeruleus to the richer blue of Thalassoma bifasciatus. 

 It even attains the blue-black sometimes worn by Teuthis 

 caeruleus and constituting the permanent ground color of a 

 large Pseudoscarus that seems undescribed by systematists. 

 Kyphosus sectatrix, Caranx ruber and Elacatinus oceanops com- 

 plete the list. 



It is noteworthy that a number of these fishes, and particularly 

 the blue-gray types, have one habit in common that is as dis- 

 tinctive as their color. Abudefduf is equally at home breaking 

 the w^ater's surface above or near the coral stacks on quiet days, 

 or deeper down among the heads themselves. Caranx and 

 Ocyurus pursue schools of minnows and make the water fairly 

 boil about them in calm weather. But the former may enter 

 one's traps upon the bottom on occasion, and the latter feeds 

 commonly upon Crustacea that never leave it. Kyphosus, 

 which is distinctly darker and less blue than the others, has the 

 same vertical range, but is neither seen at the surface as fre- 

 quently, nor appears to come at all commonly into as shallow 

 water. At Tortugas full-grown specimens appear by day, typi- 

 cally at mid-level or shghtly lower, in water approximately 20 

 feet deep, over one small patch of broken bottom, or about a 

 mass of sunken wreckage. 



It seems more than accident that four out of ten species grouped 

 by color should react habitually in a manner uncommon among 



