LYMN^EID^E OF NORTH AMERICA. 187 



Genitalia (plate X, fig. D) : Male organs : Penis-sac cylin- 

 drical, eight mill, long and two mill, wide, enlarging slightly at the 

 distal end; penis very long (10 mill.) and gradually enlarging toward 

 the head-end ; the whole penis is somewhat club-shaped ; the penis-sac, 

 as well as the penis, is made up of strong circular and longitudinal 

 muscular tissue; vas deferens very long (42 mill.) ; prostate duct rather 

 short (10 -mill.), not much dilated where it enters the prostate; pros- 

 tate irregularly cylindrical, somewhat folded, contracted posteriorly to 

 form a narrow, irregularly convoluted tube; retractor muscles two or 

 three in number, one penis retractor and one or two penis-sac retrac- 

 tors ; protractor muscles numerous, six or more on the posterior face 

 and one very large muscle on the anterior face, which is made up of 

 about six smaller muscles. The muscles of the penis-sac show much 

 variation in position (pi. XIV, fig. D), the posterior protractors being 

 widely separated (2) or close together and joined by small branches 

 (1) ; there is normally one penis-sac retractor, but two may be present, 

 as shown in figure 2. 



Female organs : Oviduct rather long, the convoluted uterine por- 

 tion very large; receptaculum seminis very large, round, its duct ten 

 mill, long, joining the oviduct two mill, from the vaginal opening; 

 albuminiparous gland of usual form; first accessory albuminiparous 

 gland rather large, somewhat pyriform or roundly knob-shaped, its 

 walls very thick; second albuminiparous gland very small, rounded. 



The organs are colored as follows : Penis, flesh ; penis-sac, black- 

 ish ; prostate, bright orange ; receptaculum seminis, mottled flesh and 

 yellowish ; albuminiparous gland, purplish and flesh ; accessory glands, 

 light flesh ; uterine portion of oviduct, yellowish and whitish. 



The peculiarities of the genitalia of megasoma are the shape of 

 the penis and its size in relation to the penis-sac. The prostate also 

 differs in form from that of any other species. The number and po- 

 sition of the retractor and protractor muscles of the male organ are 

 also noteworthy. The length of the vas deferens is equaled only by 

 that of stagnalis. 



The genitalia of two specimens measure as follows (dissection Xo. 

 23101) : 



Rec. Pros- Penis Penis- 

 Penis- sem. rate Vas. re- sac re- 

 Penis, sac. duct. duct. def. tractor, tractor. Shell. 

 10.20 8.75 9.00 8.00 41.00 6.50 5.50 45.00 Canada 

 10.00 8.00 8.50 7.10 44.00 5.00 5.00 41.00 



