190 CALIFORNIA ACADEMY OF SCIENCES. 



The penis (plate xiv, fig. 5) as a whole is a dorsoven- 

 trally flattened structure. Its anterior three-fourths is 

 wide, forming the internal plate, while the posterior 

 one-fourth is wide at its base but rapidly tapers beyond 

 this. The posterior fourth is the external part formed 

 by the chitinous thickening of the evagination described. 

 Where the two meet, a large, square area is taken out 

 of the penis. The margins at the side of and behind 

 this are very thick. From the former arise two wide 

 processes, one on each side, which rapidly contract and 

 curve dorsally and inwards, almost meeting each other 

 in the middle line. In front of these, two other pro- 

 cesses arise from the anterior margin of the non-chi- 

 tinized space, as two backward prolongations from the 

 inner edges of the thickened lateral margins of the plate 

 in front. They extend backward, outward, and slightly 

 ventrally, terminating beyond the posterior edges of the 

 lateral processes, and almost reaching across the unchi- 

 tinized space. They are narrower than the lateral pro- 

 cesses and taper but slightly. From the posterior 

 thickened margin of the unchitinized area a third pair 

 of processes arises. These are short, rapidly tapering, 

 and continuous with the ventral edge of the transverse 

 part behind the unchitinized area, this part being, 

 as before stated, tubular. These processes lie close 

 together, each just to one side of the median line. 

 Their inner edges are slightly divergent and their outer 

 edges strongly convergent and concave. Their tips 

 reach about as far forward as the posterior ends of the 

 processes in front. There are thus six processes — two 

 in front, two behind, and one on each side — arching 

 over the unchitinized space of the chitinous penis. 

 They surround the terminal portion of the ejaculatory 

 duct, since the latter passes beneath the arch formed by 

 the dorsal processes on its way to the external tubular 



