454 IL BOSCHMA. 



horn-layer of the epidermis. When the chromatophores of the 

 cutis contract, the pigment of the epidermis remains on the 

 same spot and the color of this region retains its black shade. 

 It is only covered by a thin horn-layer and it is therefore much 

 more conspicuous than the pigment of the chromatophores of 

 the cutis, which is covered by the whole ectodermal layer. 



The useful effect of these color changes in Ptychozoon is a 

 matter of course. The lizards live on the trunk and larger 

 branches of the trees. When they are in shady places they are 

 hidden by their almost uniformly dark color. In the sunlight 

 their light-gray hue equals that of the mossy background. They 

 become still more inconspicuous by the possession of the queer 

 zigzag dark stripes which procures them almost the same color 

 and design as the bark of a tree overgrown with lichens. 



LITERATURE CITED. 

 . Babak. 



'10 Zur chromatischen Hautfunktion der Amphibian. Ein Beitrag zur allge- 

 meinen Physiologic der Nerventatigkeit. Arch. f. d. ges. Physiologic 

 des Menschen u. d. Tiere, Bd. 131. 

 R. F. Fuchs. 



'14 Der Farbemvechsel und die chromatische Hautfunktion der Tiere. Handb. 

 d. vergl. Physiologic, herausg. von Hans Winterstein, Bd. Ill, Erste 

 Halite, II. Teil. 



F. Melchers. 



'99 Uber rudimentiire Hirnanhangsgebilde bei Gecko (Epi-, Para- und Hypo- 

 physe). Zeitschr. f. wiss. Zool., Bd. 67. 



G. H. Parker. 



'06 The Influence of Light and Heat on the Movement of the Melanophore 



Pigment, Especially in Lizard. Jour, of Exp. Zool., Vol. 3. 

 G. van Rynberk. 



'06 Ueber den durch Chromatophoren bedingten Farbenwechsel der Tiere 

 (Sog. chromatische Hautfunktion). Ergebnisse der Physiologic, Jahrg. 5. 



F. K. Studniczka. 



'05 Die Parietalorgane. Lehrb. d. vergl. mikr. Anat. d. Wirbeltiere, herausg. 

 von Albert Oppel, 5. Teil. 



G. Thilenius. 



'97 Der Farbenwechsel von Varanus griseus, Uromastix acanthinurus und 

 Agame inermis. Morph. Arb., Bd. 7. 



