MILLIPEDS — HOFFMAN l87 



expressed verbally in an intelligible manner. Although H. C Wood, 

 the describer of the first known pachydesmid, himself recognized the 

 taxonomic value of female genitalia, and provided woodcut illustra- 

 tions of them in his "Myriapoda of North America" (1865), only 

 sporadic attempts to develop the knowledge of the structure and 

 systematic utility of the cyphopods have been made by his American 

 successors. These structures, as shown in the accompanying draw- 

 ings, pronounce their own silent indictment of their long and un- 

 seeming neglect. 



The gonopods of the male sex in Pachydesmus are unusual in their 

 development of a secondary tibio tarsus which equals or exceeds the 

 primary branch in size. In other respects the gonopods are more or 

 less typical for the family. The coxae are large, and loosely attached 

 to each other by membrane only. 



On the anterior surface each coxa bears two long macrosetae and a 

 fairly large coxal apophysis or condyle of various shape. As a general 

 rule, this process is largest in specimens from the center of the generic 

 range, where it is often crenulate as well. In clarus, the coxal apophysis 

 is smallest, forming merely a small subconical lobe. 



The telopodite joint is massive and composed of three distal 

 branches. The smallest of these is the prefemoral process, arising 

 adjacent to the swollen and setose prefemoral portion, and directed 

 distad, bent at an obtuse angle at about its midlength, becoming 

 attenuated and acuminate terminally. The main division of the 

 telopodite is nearly straight and is divided into a densely setose basal 

 portion probably consisting of the prefemur and femur, and a thin, 

 bladelike distal portion representing the tibiotarsus. On the lateral 

 side of the telopodite, near its base, a large process originates, directed 

 first proximad and then, by a strong bend, distad parallel to the main 

 blade. This large process is structurally similar to the chitinized 

 tibiotarsal area, and may be tentatively considered as a secondary 

 tibiotarsus. Distally it may be simple and acuminate, or bifid and 

 elaborated. 



The telopodite portion of the gonopod presents several variable 

 features. The relative length of the prefemoral portion with respect 

 to the entire joint (as determined with an ocular micrometer) varies 

 geographically, and again the variation is centrifugal in that in 

 laticollis and retrorsus the prefemur attains its greatest proportion of 

 the total length — -70 percent. Toward the periphery, this ratio 

 decreases to 60 percent in crassicutis and incursus, and 58 percent in 

 clarus, the decrease being roughly proportional to the magnitude of the 

 geographic separation involved. Another feature showing strikingly 

 similar geographic parallelism is the denticulation of the anterior edge 

 of the tibiotarsus. This edge becomes serrate in most of the marginal 



