14 BULLETIN OF THE BUREAU OF FISHERIES. 



FISH NEWLY TAKEN. 



The specimens used in this study were taken on sandy beaches near the laboratory. 

 The majority of them were brownish gray in color, mottled with areas of darker and 

 lighter shades. Occasionally a specimen was taken which showed only a very slight 

 or no brownish tone. 



In the layer immediately beneath the epidermis in these specimens the melano- 

 phores in the darker areas were nearly or quite maximally expanded, while those in 

 the lighter areas were expanded to a lesser degree. In the lightest areas many of the 

 melanophores were contracted to such an extent that nearly all of the pigment was 

 concentrated in the central area. The melanophores lay immediately beneath the 

 epidermis and were not obscured by other structural elements. 



In the majority of the specimens examined most of the xanthophores in the layer 

 immediately beneath the epidermis were contracted to such an extent that the major 

 part of the pigment was concentrated in the central area. From this central pigmented 

 area irregular aggregates of pigment granules extended peripherally into the proximal 

 portions of one or more radial processes. In this condition the pigmented area is so 

 irregular in form that the radial arrangement of the parts of the chromatophore is not 

 apparent. In those specimens which showed a marked brownish tone the xanthophores 

 just beneath the epidermis were expanded to a moderate degree, while in those which 

 showed little or no brownish tone they were almost maximally contracted. The xantho- 

 phores lay appreciably deeper than the melanophores, and many of them were partly 

 covered by the latter. Many of them also were partly or completely overlain by 

 guanophores. 



The guanophores in the layer immediately beneath the epidermis occurred either 

 isolated or in small groups, usually without any apparent arrangement which could be 

 correlated with the arrangement of chromatophores or their component parts. How- 

 ever, in some instances guanophores were arranged in a radial manner about chromato- 

 phores with which they were intimately associated. Guanophores were present in 

 sufficient numbers to occupy the greater part of the surface area beneath the melanophores 

 as well as between them. They were apparently less abundant and somewhat more 

 opaque in the darker than in the lighter areas. 



Among the chromatophores lying superficial to the proximal areas of the scales 

 and, consequently, beneath the overlapping areas of other scales the melanophores 

 were well expanded while the xanthophores were expanded to an appreciably greater 

 degree than the xanthophores in the layer just beneath the epidermis. Relatively few 

 guanophores occurred superficial to the proximal areas of the scales. These also 

 appeared less opaque than those in the layer just beneath the epidermis. The chroma- 

 tophores in the deeper layers of the skin are well expanded. 



Obviously the darker shades in the color pattern of a fish newly taken are due 

 primarily to the degree of expansion of the melanophores in the darker areas. The 

 lighter shades are due not only to the degree of contraction of the melanophores in the 

 lighter areas but also to the effect of the guanophores, which to a large extent obscure 

 the melanin pigment in these areas. In specimens which show a marked brownish tone 

 this tone depends primarily upon the degree of expansion of the xanthophores. How- 

 ever, the quality of the lolor is not that of the xanthine pigment. It is probably the 



