269 



A MONOGRAPH OF THE PILL-MILLIPEDES 



{ZEPHRONTID/E) INHABITING INDIA, 



CEYLON, AND BURMA. 



By R. I. PococK, OF the British Museum of Natural History. 

 Part I. (With Plate A. ) 

 {Read before the Bomhaij Natural History Society on 14^/i of June, 1898.) 



The Millipedes, wliich form the subject of the present paper, are so 

 striking in appearance, and occupy so unique a position amongst terres- 

 trial ai-thropoda, that they must he familiar objects to all who have paid 

 any attention to the Indian invertebrate fauna. It is consequently not 

 necessary for me here to occupy any time and si)ace in pointing out 

 the chief characters of the class to which they belong. Suffice it to say 

 that the only group with which the Pill-Millipedes are likely to be con- 

 founded are the Woodlice, and although the resemblance between a Pill- 

 Millipede and a Woodlouse is at first sight striking enough on account 

 of the peculiar formation of the body, which renders it capable of being 

 rolled up in a ball, there can in reality be no difficulty in distinguishing 

 the two if the underside of the segments be examined. For it 

 will bo apparent at once that whereas in the Woodlouse, which 

 belongs to the class Crustacea^ there is only one pair of legs to each 

 segment, in the Millipedes most of the segments are provided with 

 two pairs of limbs. Moreover, the hinder end of the body in the 

 crustacean is composed of a number of small segments more or less 

 closely crowded together, but in the Pill-Millipede the last seg- 

 ment is much enlarged, and acts as a kind of protective cover to the 

 lower side of the body when it is spherically rolled. Of course there 

 are other differential characters between the two not less striking than 

 that already mentioned ; but it is needless to enter into them here. 



The Pill-Millipedes of India, Ceylon, and Burma are referable to 

 two genera belonging to the family Zephroniidcc. These genera are 

 Arthrosphoira and Zephvonia. They may be easily recognized by the 

 following characters : — ■ 



a. — ^Apex of the legs broad and truncate, the upper angle bearing a 

 long spine, above the claw, there being a considerable space between the 

 claw and the spine (PI. a, fig. 11). In the female the vulva is compos- 

 ed of three distinct pieces placed together in the form of a cone. In the 



