Monocotyle Floridana, a New Monogenetic Trematode. 7 



ous chorion of the egg is formed from the secretion of the epithelial 

 lining of the ootype, as well as from that of the shell-gland. 



Extending from the ootype to the birth-pore (figs, i and 8, b. p.) is 

 the uterus (figs, i and 8, u.). This vessel is a long tube of large size at 

 its point of origin at the ootype, which makes two complete turns, first 

 running forwards, then backwards, and finally forwards again, passing 

 ventral to the intestine and dorsal to the receptaculum seminis and 

 opening to the outside at the birth-pore. Its diameter decreases towards 

 its forward end, and throughout the greater part of its extent it is a very 

 narrow tube. It possesses, however, a chitinous lining which renders it 

 a conspicuous object under the microscope. The birth-pore is situated 

 in the ventral surface of the body in the median line near the hinder end 

 of the pharynx. 



The vagina (fig. 8, v.) is very short and leads from the vaginal pore 

 (fig. 8, v. p.) on the left side of the body near the hinder end of the 

 pharynx across to the right side of the body and into the large cylindrical 

 receptaculum seminis (figs, i and 8, r. s.). This is a prominent thin- 

 walled organ, always filled with sperm, which lies just back of the pharynx 

 on the right side and near the ventral surface of the body. Its hinder 

 end is rounded and about 0.08 mm. in diameter, and is connected with 

 the uterus by means of a short canal. 



The yolk-glands consist of small, closely compacted spherical follicles 

 and are very voluminous. They extend from the forward portion of the 

 pharynx to the hinder end of the body, occupying the areas lateral to the 

 intestinal trunks as far back as the hinder end of the ovary and testis. 

 Posterior to these organs they fill the entire body, completely immersing 

 the hinder portions of the digestive tract. The two transverse yolk-ducts 

 lie in very nearly the middle of the body. They meet near the hinder end 

 of the ootype and form a very short common duct, which enters the 

 oviduct almost at the point where it enters the ootype. No yolk reservoir 

 is present. No genito-intestinal canal is present. 



The genital organs of this worm exhibit several interesting and 

 unusual features. As will have been noticed, there is here no common 

 genital pore. The vas deferens, instead of opening to the outside together 

 with the uterus, finds an outlet, as I have determined with perfect 

 certainty, through the vaginal pore, and the sperm undoubtedly passes 

 directly from the vas deferens through the vagina and into the recepta- 

 culum seminis of the same animal. The self-fertilization which is thus 

 brought about may be necessary because of the total lack of a penis 

 and a vesicula seminis. 



The receptaculum seminis, as in other monogenetic trematodes, is 

 nothing more than a distended portion of the vagina and is invariably 

 filled with sperm in all the worms I have studied. The vagina is peculiar 

 in that it opens into the uterus near the forward end of the ootype instead 

 of into the oviduct or the yolk-duct near the hinder part of that organ. 



The birth-pore is what is left of the common genital pore after the 

 migration of the terminal end of the vas deferens to the vaginal pore, 



