OF NORTH AMERICA. 143 



The muscles of the penis-sac in stagnalis are unusually large and strong. 



Female organs: Vagina very short and wide; oviduct very long, 

 rounded at its lower portion, but much convoluted at its upper portion, 

 where it forms the uterine portion ; receptaculum seminis roundly pear- 

 shaped, its duct narrow and as long as the penis-sac, about a third as 

 long as the prostate portion of the vas deferens and as long as the free 

 portion of the oviduct; this duct enlarges at its junction with the ovi- 

 duct to form the vagina; albuminiparous gland a large linqueform 

 body; first accessory albuminiparous gland very large, flatly rounded, 

 firmly attached to and embracing the oviduct; second albuminiparous 

 gland small, almost round, attached to but not embracing the oviduct. 



Hermaphrodite organs : The ovotestis is embedded in the digestive 

 gland; its duct is at first a narrow tube which divides to form the 

 uterine portion of the oviduct and the prostate. 



The organs are brightly colored, the albuminiparous gland, ovo- 

 testis, first accessory albuminiparous gland and receptaculum seminis 

 being orange, the prostate orange shading into black, the vagina dirty 

 white and the penis-sac flesh-colored. The muscles, vas deferens and 

 other ducts are white. The colors are somewhat variable. 



The muscles of the penis-sac exhibit considerable variation (pi. 

 XIV, fig. A). The retractors vary from one to three in number, 

 although two seem to be the normal number present ; the anterior pro- 

 tractors appear quite constant in form and number, but the posterior 

 protractors vary from one to five. It is noteworthy that where a 

 number are present they are much smaller and narrower than is the 

 case where only one or two are present. This increase in number is 

 probably due to a splitting of the large muscles. The posterior pro- 

 tractors may be attached to the right border of the columellar muscle 

 or they may be attached to the numerous small transverse muscles 

 of the columellar region (1, M). The penis retractor varies to some 

 extent ; normally it arises directly as a branch of the penis-sac retractor 

 (pi. XIV, A., 2, 3), but it is sometimes split into two branches at 

 its junction with the penis-sac retractor, as shown in figure A, 1. 



The measurements of the genital organs are quite uniform; four 

 are shown in the following table i 1 



Y. 



'Dissections 23023, 23024, 23042. 



