52 ILLINOIS BIOLOGICAL MONOGRAPHS [332 



I 



Alimentary Tract. — The mouth funnel is a cup shaped muscular 

 structure (Fig. 51) which functions as an organ of adhesion. There 

 is no oral sucker. The mouth funnel is 0.08 to 0.1 mm. in diameter, 

 sub-terminal in position. There is no prepharynx, the mouth funnel 

 opens directly into the pharynx. The latter is a spherical muscular 

 organ 0.09 to 0.1 mm. in diameter. As described by Osborn for C. 

 insignis, it is followed by a very short esophagus, which in the anterior 

 part has a cuticular lining and in the posterior part where the esopha- 

 gus passes over into the intestine, a lining of flattened epithelial cells. 

 The intestine is an elongate sac or tube extending on the dorsal side 

 of the body 0.1 to 0.2 mm. posterior to the caudal edge of the testis. 

 It varies but slightly in caliber, averaging about 0.075 mm. in diameter. 

 The wall consists of a fibro-membranous sheet upon which rests a layer 

 of columnar epithelial cells. The large deeply staining nuclei of the 

 epithelial cells lie in the basal part while many delicate elongate proc- 

 esses extend out into the lumen of the canal. 



Male Reproductive Organs. — The testis is large, single, median, its 

 anterior margin lying at the center of the adhesive disc. It is almost 

 spherical and measures 0.25 to 0.35 mm. in diameter. Cells of various 

 sizes and with the chromatin material in various stages of division, as 

 well as mature spermatozoa are to be seen in sections. The sperm duct 

 arises at the anterior part of the testis and turns to the left, entering 

 the side of a long, much-coiled seminal vesicle (Fig. 48). This vesicle 

 is a large tube, 0.1 to 0.175 mm. in diameter, extending from the region 

 of the testis to the cirrus sac. It is coiled eight to sixteen times and in 

 all mature specimens is filled with spermatozoa. Terminally it is con- 

 stricted into a small tube which enters the large cirrus sac. This latter 

 structure (Fig. 53) is 0.145 to 0.2 mm. wide and 0.2 to 0.25 mm. long, 

 has a strong muscular wall, and is pyriform in shape, the smaller end 

 opening anteriorly at the genital pore. Inside the cirrus sac there is 

 a dilated, curved portion of the duct which has muscular walls and is 

 lined with epithelial cells. Surrounding the duct and filling the cirrus 

 sac are the large cells of the prostate gland. These are pyriform and 

 average 26/x, long by 17/* wide. In living specimens the cirrus was 

 observed in the extruded condition. 



Female Reproductive Organs. — The ovary is a small organ, ovoid 

 in shape, averaging 0.16 mm. in length, 0.1 mm. in width, and 0.05 mm. 

 in thickness. It is located (Figs. 46, 52) at the right of the median 

 line, slightly anterior to the middle of the body. The oviduct arises 

 (Fig. 48) at the posterior ventral margin of the ovary and passes 

 posteriad; receives a short common vitelline duct, and then expands 

 into two or three irregular enlargements. Mehlis' gland is present, the 



