52 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 95 



ment (fig. 19 C, F). The male ducts usually discharge separately on 

 a pair of, small penes having the form of papillae or lobes arising 

 either directly from the coxae of the second legs (C, Pen), or mesally 

 behind the coxal bases (A), but in some forms the ducts open together 

 on a median penis arising between or behind the legs (J, Pen). The 

 legs of the genital segment in most cases have the typical leg form 

 (A, C), but they may be reduced in size and otherwise modified, or 

 united at their bases (J, Cxpd). In certain species the first legs also 

 are modified in a manner suggestive that they take some part in 

 copulation (J, iL, K). 



The female genital ducts open either on the coxae of the legs of 

 the genital segment, or on the sternal surface behind the leg bases. 

 Usually the legs of the genital segment are not modified in the female, 

 but there are exceptions, as shown in Parajulus impressus (fig. 19 F), 

 in which the telopodites of the genital appendages are reduced to small 

 lobes {Tlpd) and the oviducts open into large cavities on extensions 

 of the united coxopodites {Cxpd). In forms in which the ducts open 

 behind the legs, the apertures are usually contained in a complicated 

 integumental structure (see Brolemann and Lichtenstein, 1919, and 

 Seifert, 1932). 



Intromission is accomplished in the ordinary diplopods (Proter- 

 andria) by the modified legs (gonopods) of the seventh body segment 

 of the male, which transfer the sperm from the penes or penis of the 

 third segment into the genital apertures of the female. In two of the 

 diplopod groups, however, the relatively generalized Pselaphognatha 

 and the Opisthandria, according to the classification of Attems ( 1926) , 

 none of the appendages is modified for the purpose of intromission, 

 though in members of the first group the coxae of the eighth legs 

 have external pouches, which Attems suggests may have some repro- 

 ductive function. In the Opisthandria one or two pairs of legs at the 

 posterior end of the body in the male are specially modified to serve 

 as copulatory organs. With these legs the male is said to grasp the 

 genital coxae of the female, while he inserts the spermatozoa into 

 the female gonopores with his mandibles (Attems, 1926). 



The gonopods of the seventh body segment of proterandrious male 

 Diplopoda are analogous in their function to the gonopods of mala- 

 costracan Crustacea and the pedipalps of male spiders ; in their struc- 

 ture even they are not dissimilar from these organs. The pair of 

 appendages converted into gonopods is usually the first pair of legs 

 of the seventh segment ; the second legs of this segment are generally 

 of usual form, but they may be absent, or modified also to form a 

 second pair of gonopods. A typical diplopod gonopod (fig. 19 E) 



