124 PROCEEDINGS OF THE NATIONAL MUSEUM vol. i04 



then turns abruptly backwards, at the same time greatly increasing 

 in size. It then proceeds posteriorly as a long oval sac with a thick 

 muscular wall. The interior in the sectioned specimen is filled with 

 sperm. Upon approaching the vicinity of the penis, the seminal 

 vesicle narrows to an ejaculatory duct that curves ventrally and joins 

 the prostatic duct inside the penis papilla. The prostatic vesicle is a 

 very small oval sac lying beneath the narrowed distal part of the 

 seminal vesicle. It has a thick muscular wall and a glandular lining 

 filled with eosinophilous granules. Its duct immediately joins the 

 ejaculatory duct and the common duct so formed proceeds to the tip 

 of the penis papUla. The latter is a well formed conical projection 

 housed in a male antrum that follows its contours. The male antrum 

 shortly opens below by the male gonopore. 



The female gonopore is situated shortly behind the male gonopore. 

 It leads into a short tubular female antrum that at once continues 

 as the vagina. The latter is a ciliated tube of extraordinary length 

 that runs forward above the seminal vesicle to a point slightly anterior 

 to the vesicle's anterior end, then it turns abruptly posteriorly and 

 parallels its former course until it reaches a level of about that of the 

 female gonopore, where it terminates on receiving the two oviducts 

 separately. The vagina is ciliated throughout and accompanied along 

 its entire course by an immense mass of cement glands that practically 

 fUl all the space between the seminal vesicle and the dorsal body 

 wall, as well as extending far anterior to the curve of the vagina. 

 Lang's vesicle is wanting and there is no other extension of the vagina 

 caudad of the entrance of the oviducts. The uteri extend forward 

 alongside the pharynx nearly to the level of the most posterior eyes 

 (fig. 81,^). 



Distribution: Collected by W. G. Hewatt on Mar. 13, 1946, at 

 East Point Beach, Boqueron, Puerto Rico, under beds of Mytilus 

 between tides. 



Holotype: One whole mount deposited in the U. S. National 

 Museum, No. 24620; also one set of sagittal serial sections of the 

 copidatory region in that institution (four slides), No. 24621. 



Remarks: This species combines the characters of several genera 

 of the Stylochidae without fitting satisfactorily into any of them. 

 A greatly reduced prostatic vesicle is also seen in Parastylochus, 

 Enterogonia, and Cryptophallus; an excessively long vagina occurs in 

 Meixneria and Idioplana; the prostatic vesicle lies to the ventral 

 side or at least the anterior side of the seminal vesicle in Cryptophallus; 

 but in no other stylochid genus is found a combination of these charac- 

 ters plus an enormous increase in the size of the seminal vesicle. It 

 therefore appeared necessary to create a new genus for the species. 



