302 WILLIAM A. HASWKLL. 



to tlie next or third segment, the main part of which bulges 

 out laterally like the second, and bears a similar pair of cirri 

 {c~). On this follows a small annulus, probably belonging to 

 the fourth segment. The main part of the latter is much 

 broader than the segments in front, bulging out prominently 

 at the sides. In the female this segment is devoid of ap- 

 pendages, but in the male it bears a pair of remarkable 

 organs, the claspers {cL). These are situated laterally in a 

 position corresponding to that of the cirri on the other seg- 

 ments. They are not unlike the anterior legs in their general 

 shape, but are considerably larger. They are of cylindrical 

 shape, stouter at the base than towards the free end. The 

 distal extremity is obscurely divided into two lobes, tipped 

 with a few non-motile cilia; close to this, situated laterally, 

 are two small rounded elevations. A large unicellular gland 

 (fig. 14, gl. cl.) lies in the basal part of the interior of the 

 clasper, its duct opening at the distal end. 



The following segment, the fifth, is as wide as the third, 

 but somewhat shorter. It bears laterally a pair of cirri (c^j, 

 similar to those on the more anterior segments. The part of 

 the body which lies behind this is sharply marked off from 

 the rest, as will subsequently be explained. It cannot be 

 looked upon as a single segment, and it will be preferable to 

 term it the posterior or caudal region. It nearly equals in 

 length the two preceding segments put together, but is much 

 narrower, being in fact the narrowest part of the body. It is 

 divided by slight constrictions into six fairly regular annuli, 

 which, however, may become obliterated when the body is 

 greatly extended. At its posterior end, rather towards the 

 dorsal side, is the anal aperture. At the sides of this lie the 

 large postei'ior legs {I. p.) . These are non-retractile, and in a 

 state of rest usually extend first outwards and backwards, 

 and then, towards their extremities, bend forwards. They 

 are much larger than the anterior legs (as long as the entire 

 caudal region) ; subcylindrical, stout at the base, constricted 

 towards the free end, which is expanded into a flattened 

 adhesive disc, the edge of which is divided by notches into 



