DEPAKTMENT OF MARINE BIOLOGY. 161 



The family of the Labridse is rich in Hawaiian genera and species, to which 

 many of the observations mentioned below refer. Not the least interesting 

 among them are the hatchet-faced genera, Novaculichthys, Cymolutes, Iniis- 

 tius, and Xyrichthys, which commonly escape pursuit, when danger becomes 

 too urgent, by darting beneath the surface of loose sand, where the difficulty 

 in locating them indicates they possess no mean power of movement. In 

 this highly specialized reaction they simply exhibit in extreme form a tjq^e 

 of behavior common within the family under certain circumstances, for both 

 in the West Indies and in Hawaii many labrids bury themselves in the sand 

 at night. To West Indian forms in which this habit has been noted and to 

 species of the genera enumerated above the following may be added on the 

 strength of observations made in the aquarium at Honolulu: Cheilio inermis, 

 Coris venusta, Julis eydouxii, J. lepomis, J. pulcherrima, Thalassoma hallieui, 

 and T. dwperrey. 



Special attention was paid to analysis of the diversity of habit which 

 appears within the families of Mullidse and Teuthidse, both rich in local 

 forms. For the point has been made that differences in habit between related 

 species are often so slight that differences in color with which they may be 

 associated can not be explained by correlation with them. In the case 

 of the fishes here mentioned such observations as were possible under 

 existing conditions go far toward showing that (providing their habitats are 

 accessible), however like one another they may appear in other respects, 

 distinct differences in habit exist in general between any two species strik- 

 ingly different in coloration. 



It is noticeable that color is correlated with habit upon the same terms in 

 the West Indies and in Hawaii. This is suggested by the fact that there are 

 such pairs of species as Abudefduf saxatilis and A. abdominalis of the respec- 

 tive regions, or Ewpomacentrus fuscus and Pomacentrus jenkmsi, which are 

 so like one another in appearance that with one in sight and only the memory 

 of the other in mind it is impossible to cite any difference between them, except 

 in geographical distribution. 



Approaching the same subject from another point of view, it is to be noted 

 that blue-gray seems as definitely correlated in one place as in the other with 

 the habit of floating high in the water. The case is beautifully exemplified 

 by comparing Abudefduf abdominalis with A. sordidus, both Hawaiian species. 

 Like A. saxatilis, the former rises clear to the surface on occasion and com- 

 monly swims at high levels. A. sordidus is by comparison a bottom species 

 and matches the blue-gray in the pattern of the other by more or less dusky 

 ohve. In color it is much like A. taurus of the West Indian region, which I 

 have seen too rarely for comparison at length in respect to habits, but con- 

 cerning which my experience contains nothing inconsistent with the assump- 

 tion that it too is much more closely confined to the bottom than A. saxatilis is. 



Another pair of Hawaiian species, between which the same difference in 

 habit is coupled with corresponding difference in coloration, includes Chromis 

 ovalis and C. elaphrus. The foraier rises freely to the upper levels in the 

 water and as an adult is distinctly blue-gray without markings of other colors ; 

 the latter, within the limits of my observations, and I have seen many individ- 

 uals of the species, always stays near the bottom, usually a rocky one, and 

 slips in and out of tiny crevices with great agility. It is pale olive in colora- 

 tion, becoming more yellow on the fins, and across the eye it has a vertical 

 black bar the width of the pupil. 



The red genera, Myripristis, Holocentrus, Priacanthus, and Amia, repre- 

 sented by M. symmetricus, H. diadema, H. microstomus, P. alalaua, and A. 



