698 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxv. 



Its diameter is not more than a third that of the basal papilla, so 

 that its point is quite sharp despite the fact that it is enlarged a trifle. 

 On the ventral surface of the basipod are projections similar to those 

 connected with the other type of peg, and a large triangular plate 

 extending across the surface, both projections and plate being- cov^ered 

 with rough chitin tubercles. The tissues around this kind of a peg 

 are more transparent than in the other species and through them can 

 be seen a muscle running from the very tip of the basal papilla diag- 

 onally backward to the posterior surface of the basipod, where it is 

 attached to a small chitin thickening of the cuticle just at the tip of the 

 triangular plate. This is the muscle which gives motion to the peg, 

 and by it the narrow terminal part can be at least partially withdrawn 

 into the wider basal portion. Alongside the muscle can be seen a good- 

 sized nerve fiber which extends into the basal portion of the peg and 

 indicates that the latter possesses a good sense of touch. 



The same muscle and nerve exist in the previous type, but can not be 

 seen as readily through the more opaque tissues (Plates XV, XX, and 

 XXI). The semen capsule is quite a deep, pocket-shaped cavity on the 

 posterior border of the third pair of legs opposite the peg. While 

 the peg is confined exclusively to the distal basipod joint, both seg- 

 ments of the basipod share in the formation of the capsule, according 

 to Claus. 



In most species the bulk of the capsule is on the distal joint, but in 

 at least two species, fundidi and megalops, it is almost wholly on the 

 basal joint. The lumen of the capsule is closed by flaps projecting 

 over it from the surrounding tissues. These flaps are held open by 

 the peg on the posterior legs while the capsule is being filled with 

 sperm. 



In addition to this peg and capsule there are various specific modi- 

 fications of the three posterior legs. 



These take the form of processes of various shapes attached to the 

 anterior, the posterior, or to both surfaces of the basipods. In mega- 

 lojjs the basal joint of the third legs is well rounded posteriorly and 

 has a large thumb-shaped projection at its distal anterior corner, giv- 

 ing it nuich the appearance of a hand denuded of its fingers (Plate XI). 



In lattcauda the basipods of the third legs project posteriorly in two 

 long flaps on each joint, the outer one narrow and finger-like, the inner 

 one broad and well rounded (Plate X). 



There are two exactly similar but rather larger projections on the 

 posterior border of the basal joint of the second legs. 



In versicolor there is a small finger projection from the outer end of 

 the basal joint of the third legs on their posterior surface and a very 

 large conical one in a similar position on the second legs. The distal 

 basipod joint of the third legs also has a rounded knob on its anterior 

 surface (Plate XX). 



