396 ARTHTTB DENDY. 



the fifteenth pair of legs are rendered conspicuous by a pair 

 of white papillae lying in the angles between the leg and body 

 at each side of the genital aperture ; the others may also be 

 indicated by white papillae. 



The predominant colours of the skin are red and indigo- 

 blue, the former passing into yellow and the latter into black 

 in some specimens. The pattern and relative amounts of the 

 different colours vary greatly, but as far as my own personal 

 experience goes the following appears to be the fundamental 

 arrangement from which other types may be derived (compare 

 fig. 1). On the dorsal surface is a series of segmentally 

 arranged diamond-shaped patches, in which the red colour 

 predominates. Each patch is made up of two triangles, whose 

 bases face one another on each side of the narrow mid-dorsal 

 longitudinal groove, while their apices lie over the legs, and 

 at about one third of the distance from the mid-dorsal line to 

 the insertion of the legs. The separation of the diamonds 

 from one another is by no means complete, so that there are 

 really two continuous bands of red, one on each side of the 

 mid- dorsal line, with their outer margins deeply indented 

 between the legs. 



The edges of the mid-dorsal groove are often darkly 

 pigmented, and may give rise to an apparently single median 

 dark line when the lips of the groove are closed together by 

 contraction. There is commonly, also, a dark edging to the 

 red diamonds on their outer margin, forming a zigzag longi- 

 tudinal stripe. This typical pattern may be almost, if not 

 quite, obliterated by the replacement of the red pigment by 

 dark indigo-blue, but even in very dark specimens it may still 

 be represented by a row of small, pale yellow or red spots, 

 each of which occupies the apex of one of the red triangles 

 in typical specimens. The ventral surface is mottled in the 

 different colours, but is paler than the dorsal, and exhibits no 

 characteristic pattern. There is in the middle line a row of 

 still paler areas, placed one between the legs of each pair but 

 the last. Patches of dark indigo-blue are usually present on 

 the under surfaces of the legs, near to their bases, 



