414 FRANCIS B. SUMNER 



For an understanding of the color changes undergone by this 

 species, some account is necessary of the permanent markings or 

 aggregations of visible pigment. These markings are so complex 

 in their arrangement that a satisfactory account of their condition 

 in any one color phase would be a most laborious task, and an 

 adequate description of their changes under various circumstances 

 would be practically impossible. These markings may, however, 

 be referred to several rather distinct types according to their 

 general appearance and behavior. 



1 We have a considerable number of circular, elliptical or 

 pear-shaped spots, each bounded by a series of small white dots. 

 The areas within these dotted outlines vary in shade, according to 

 conditions, from a nearly pure white to a shade, uniform with the 

 ground color of the fish, however dark that color may happen to 

 be. Some of the most striking alterations of appearance which 

 are manifested by this fish are due to the changes undergone by 

 this first type of spots. The rings of dots bounding these areas 

 I shall call the 'annuli,' the areas within the latter being the 'intra- 

 annular areas. ' For the sake of brevity, I shall refer to the mark- 

 ings thus constituted as the 'pale spots,' where no confusion will 

 result from this designation. So far as I have observed, the white 

 dots making up the annuli never wholly disappear, even in the 

 darkest condition assumed by the fish on any bottom (figs. Ic, 

 9d). At times, the entire areas inclosed by them are almost pure 

 white, but the central region usually remains somewhat darker. 

 Under certain conditions some of these spots have a rather strik- 

 ing resemblance to patches of lichen. 



The markings of this type are arranged with a considerable de- 

 gree of regularity, and it is likely that their disposition is essen- 

 tially similar in all members of the species. They may be dis- 

 tinguished as marginal and central, according to their position. 

 A regular alternation of annuli of different sizes (primary, second- 

 ary and tertiary) will be noted along the margin of the body. The 

 inner edges of certain of the largest marginal annuU expand into con- 

 conspicuous white crescent shaped areas. This is particularly 

 true of one pair of primary annuli lying some distance behind the 

 middle of the body. 



