REPTILIAN LIVERIES. 153 



ing only as a barely perceptible slit. As the 

 shadows of evening grow the slit widens, till at 

 last the pupil becomes perfectly round. 



Both these Geckos are instances of permanent, 

 protective coloration. Variable protective colora- 

 tion occurs in some Geckos and many Lizards, 

 but is apparently not met with among Snakes. 

 One of the best examples afforded by the Lizards 

 is that of the variable. 



Calotis mystaceus, of Burma. Mr Mason 

 thus describes it : " The male ... is sometimes 

 a beauty. He may be often seen jerking his 

 head up and down, with the head, pouch, and 

 whole front of the body a glowing ultramarine 

 blue, contrasting beautifully with the reddish- 

 brown of the hinder part of the body and tail. 

 From the nose to the shoulders below the eye, 

 is a broad white band, which is interrupted by 

 those reddish-brown patches, in line with the 

 white band, before reaching the uniform reddish- 

 brown of the hinder part of the body. Occa- 

 sionally the white band below the eye assumes a 

 brownish colour, and the animal appears to have 

 a broad band down each side. He does not 

 always, however, appear in this x gay dress. 

 While I am writing, I see him coming down the 

 trunk of one of the trees in a very faded garment. 

 His skin suggests a bright calico after it has. 

 been washed, whose colours succumb to soap. 

 The blue is there, but it is no longer the bright 

 blue of yesterday. It has changed to a dull, 

 light indigo colour. He runs across the grass to 

 the foot of another tree, and stops on the bare 

 ground at its base, where for a minute or more 



