98 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Ser. 



shapes except in those regions where no such pressure is exerted. 

 In regions where no pressiire is exerted, they are rounded and He 

 close together in the wide meshes of the connective tissue. 



I was unable to verify Keller's observations that the leucophores 

 were rounded in those regions where the mechanical resistance is 

 less, for those isolated cells which were noted by me showed in 

 reality even greater irregularity, when seen in vertical section, 

 than those in the leucophore layer proper. That the peculiar plate 

 or block-like shape and the arrangement of these in parallel rows 

 may be due to the pressure of the dense connective tissue from 

 below seems likely, but only careful observations of the skin in 

 various stages of development can determine this point. 



The white, dust-like material of Pouchet, the white pigment of 

 Briicke, or the granules of Keller, which were described in the 

 leucophores, were not noted by me in Anolis. The cytoplasm of 

 these cells even in the fresh state was clear and apparently free 

 from granules. This finding is interesting in that one would 

 expect the reflecting power of these cells to be due to the denser 

 granules, and probably such granules do exist but were invisible 

 because of methods I employed in the study of these cells. 



No differences in shape or position were noted in the leucophore 

 layer in the green and brown state. The cells of the layer seem 

 to retain their characteristic appearance and relationship no mat- 

 ter what color state of the skin existed. Carlton makes the same 

 observation for his so-called ochrophore layer. 



The blue coloration of the melanophores by reflected light de- 

 scribed for the scales of the ventral aspect of the body is undoubt- 

 edly due to the leucophore layer as is also the white appearance 

 of these scales. This will be touched upon later. 



The Melanophores. — Lying between the leucophore layer and 

 the underlying connective tissue layer, and partially imbedded in 

 both, are the melanophores described by Keller for the chameleon 

 (Figs. 10, II, 12, 13, 14, 15, 16, 17). 



In Anolis three types of pigment cells are found, namely, those 

 in the dorso-lateral scales which differ from those in the ventral 

 scales by their smaller size and more delicate branching, those in 

 the ventral scales, and a third type which is commonly situated 

 just beneath the epidermis between the scales. The melanophores 

 show a striking resemblance to the Purkinje cells as seen in Golgi 

 preparations. A line passing through the cell bodies of the ma- 

 jority of them would be more or less parallel to the epidermis except 



