MONOGRAPH OP THE GENUS PEEIPATUS. 443 



sometimes so numerous that the ground colour in that region 

 is brown, though green elsewhere on the back. 



The pigment is always present, whether on the papillae or 

 between in minute square, pentagonal, and hexagonal patches. 

 The darkness of the skin is probably mainly due to the number 

 of these patches present in any given area. 



The antennae are always green, the brown being almost 

 entirely absent from them, and they are the first to acquire the 

 green colour in the embryo. In fact the young at birth are 

 almost quite white excepting the antennae. 



The colour seems hardly at all affected by the action of spirit. 

 The flesh-coloured brown of the ventral surface is sometimes 

 slightly reddened when the animal is first put into spirit, but 

 the red tinge soon vanishes, being apparently dissolved out 

 by the spirit, which in such cases becomes slightly coloured. 



Ridges and Papillae of the Skin. — The skin is thrown 

 into a number of transverse ridges, along which the primary 

 wart-like papillae are placed. 



The papillae, which are found everywhere, are especially 

 developed on the dorsal surface, less so on the ventral. The 

 papillae round the lips differ from the remaining papillae of the 

 ventral surface in containing a green pigment. Each papilla 

 bears at its extremity a well-marked spine. 



The ridges of the skin are not continued across the dorsal 

 middle line, being interrupted by the whitish line already 

 mentioned. Those which lie in the same transverse line as 

 the legs are not continued on to the latter, but stop at the 

 junction of the latter with the body. All the others pass round 

 to the ventral surface and are continued across the middle line; 

 they do not, however, become continuous with the ridges of the 

 other side, but passing between them gradually thin off and 

 vanish. The ridges on the legs are directed transversely to 

 the long axes of the legs, i. e. are at right angles to the ridges 

 of the rest of the body. 



The papillae of the dorsal surface are not arranged in a 

 single row in the ridges, but in more than one row, in fact a 

 ridge varies in thickness in different parts of its course. 



