iSqS-J NEW-YORK MICROSCOPICAL SOCIETY. 59 



to get her little ones out of clanger by sidling first against one, 

 then against another, until she had them all pushed into a rut of 

 the road. Here the little mother with her young squatted so that 

 they were nearly flat. Had it been a sand bed they would have 

 burrowed out of sight. In this instance the effort was to get out 

 of observation — a quite different thing. In color like the soil, 

 with the tint a little intensified by emotion, they were apparently 

 mere excrescences of the ground. 



As the chromic mimicry of the Phrynosoma is confined chiefly 

 to one color, I shall speak of it as a monochrome, in distinction 

 from the chameleon, whose mimic power of color is very marked 

 and so is to be called a polychrome. We know that soils in some 

 regions maintain a preponderating color over a large area. It is 

 an interesting fact that Phrynosomas of the same species have the 

 one fixed color corresponding to that of their natal soil. As I 

 understand it, the pigment cells, or, literally, color tubes, of the 

 chameleon are of several kinds and deeply seated in the true 

 derm or nether skin. I have under the microscope a mount of 

 the cast skin of the horned toad, P. cornutum. It is composed 

 of semi-transparent spaces, erroneously called scales, which, how- 

 ever, is a convenient term. Each of these spaces is bordered by a 

 very much thicker cuticle. The whole is suggestive of a window 

 sash, the transparent parts being the panes and their thick bor- 

 ders the lattice-work. In this thin tissue, more or less crowded 

 to one side of each pane, may be seen the brown pigment gran- 

 ules. They are of one predominating hue and of great quan- 

 tity, being in the cuticle, while the specimen of cast cuticle of 

 Anolis now under the microscope shows no pigment grains what- 

 ever. In Anolis principalis the panes, as I have called the thin 

 parts of the scales, are much thinner and more transparent, serv- 

 ing, as I conceive, their function for a window through which the 

 color changes can appear when the pigment of the under derm is 

 brought up against them. 



I think we may regard the true or under skin of Anolis func- 

 tionally as a palette, in which the different colors are like collapsi- 

 ble tubes set side by side, the tints being produced by pushing 

 the colors against this window of almost membranous tissue, for 

 to such I have likened the transparent vestment. Suppose a 

 mosaic of microscopic discs or hexagons of more colors than one 



