THE COLORATION OF REEF FISHES 565 



The feeding time of the yellow goatfish (Upeneus martinicus) 

 seems to coincide with that of the grunts and snappers, though 

 during the day individuals are sometimes seen stirring the sand 

 wdth their barbels, as though searching for food. Holocentrus 

 and Priacanthus may also be included in this group with slight 

 probability of error. The number of these red fishes examined 

 is small, but the results are consistent and a great mass of col- 

 lateral evidence supports this interpretation. 



WTiat fishes feed by day is not made clear by the tabulated 

 record; but this may be supplemented by observations which 

 permit one to state with some confidence that most Labridae, 

 Scaridae and Chaetodontidae, to mention no others, are diurnal. 



From daylight to dark the activity of Iridio and Thalassoma 

 is scarcely interrupted. Not one broken sea urchin is exposed 

 upon the reefs, that they do not gather about and feed upon. 

 The same ig true of Lachnolaimus, except in so far as its com- 

 parative rarity limits its appearance. Scarus may be seen 

 floating listlessly near the bottom at daybreak, and combining 

 forces with Sparisoma a dozen common species grub industri- 

 ously upon it all day long. At dusk the acti\dty of all the 

 Scarids changes; all disappear, except as an occasional one in its 

 nocturnal color-phase lies half-revealed beneath the imperfect 

 shelter of coral, gorgonian or projecting stone. Darkness also 

 modifies the behavior of the Labrids which, perhaps favored 

 by their smaller size, disappear even more completely. Species 

 of Thalassoma, Iridio and Xyricthys, three labrid genera, when 

 confined in tanks, if the bottom be covered wdth loose sand to a 

 sufficient depth, burrow into it and remain in hiding until the 

 dawn. 



To burrow or partially cover themselves with loose material 

 is not uncommon procedure among fishes. Gnathypops auri- 

 frons and maxillosa use their jaws for digging and their mouths 

 for carrying away excavated material from narrow pits they 

 make and occupy. Halieuticthys aculeatus, a batfish dredged 

 in 45 fathoms, backs into the sand and uses its pediculate pec- 

 toral fins to throw an incomplete but almost impenetrable screen 

 over its flattened body from its postero-lateral margins. Syno- 



