702 Laura Florence 



a;:d according; to Nuttall is not present in Pedi'culus. Cummings (iOl.'J: 

 260) has described a somewhat simOar condition in Lmognathus limnotragi 

 Cummings in whicli the parameres 



are of a remarkable type. Proximally they are broad blade-like pieces which meet each other 

 (but do not fuse) beneath the mesosome in a fairly long median groove, then dorsally wrap 

 themselves around the mesosome lying between them, forming a kind of sheath, from the 

 end of which the penis projects, and, hke the somewhat narrower distal ends of the parameres, 

 curls up dorsalwards. 



The parameres are two strongly chitinized regions on the lateral walls of 

 the dorsal lamella of the basal plate, and articulate anteriorly with its lateral 

 processes in the region of the seventh abdominal segment (Plate LXIV, 

 1, 2, 3, and 5). They are boat-shaped structures, with the keel external 

 and lateral, and can be seen through both dorsal and ventral aspects. 

 Distally they almost meet on the median line and proximally they diverge. 

 The distal points appear to be less strongly chitinized than the remainder 

 of the structure. In feeding experiments males approaching females 

 were frequently seen to protrude and withdraw the parameres. 



The vesica penis (preputial sac of Mjoberg, mesosome of Cummings), 

 when lying within the body, rests within the upper lamella of the basal 

 plate, its walls are thrown into folds (Plate LXIV, 1 and 3), and its anterior 

 part is invaginated within the more posterior part. When ejected (Plate 

 LXIV, 3 and 4) it passes backward and slightly downward for about half 

 its length, when it bends slightly upward again. It is from one-half to 

 three-fourths of a millimeter long and at its widest posterior part is approxi- 

 mately half as wide as its length. At its distal end on either side, directly 

 on the median lateral line, are two small lobes covered with teeth, as is 

 the whole sac with the exception of an area on the ventral surface near 

 the proximal end. The thin, smooth wall of the sac surrounds the penis 

 like a sheath for one-half of its length from the point of branching to the 

 tip. It points directly dorsad. At its distal end the sac appears to be 

 continuous with the basal plate. Above the copulatory apparatus and 

 between it and the anal opening is the pregenital fold. No postgenital 

 fold is present, unless the dorsal and ventral lamellae of the basal plate 

 be considered as forming such. 



The penis is a strongly chitinized tube made up of two half-tubes closely 

 apposed to each other (Plate LXIV, 1 and 4). It lies within the vesica 

 penis, its posterior pointed end turned toward the canal between the para- 

 meres, and its anterior part, into which the ejaculatory duct passes, in 



