6 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.60. 



to 0.90 mm. long and 0.08 to 0.13 mm. wide at its widest (anterior) 

 portion. It encloses a vesicula seminalis which is not coiled, but is 

 constricted at its middle portion, a pars prostatica and a protriisible 

 cirrus (fig. 3). Cells are present between the wall of the cirrus sac 

 and the vesicula seminalis and pars prostatica. In the unprotruded 

 state the cirrus lies coiled within the sac, and a muscular ring which 

 surrounds its distal portion can be distinctly seen. 



The ovary is spherical in shape with a diameter of 0.15 to 0.19 mm. 

 It lies in the substance of the clinging plug, on the ventral side of 

 the posterior surface of the anterior testis, toward the left or right 

 side and opposite the cirrus sac. It gives off from its postero-ventral 

 surface a short oviduct with a distant ootype surrounded by a diffuse 

 shell gland. Laurer's canal is present, but very difficult to find, even 

 in sections, due to its small size and to the fact that it is crowded out 

 by the vitelline glands and reservoir. It opens on the dorsal surface, 

 toward the left or right side, opposite the anterior end of the second 

 testis. The relations of the canal, the oviduct, the unpaired vitelline 

 duct and the shell gland, and the course of the uterus are shown in 

 figure 4 B. The receptaculum seminis is lacking. The vitellaria are 

 very well developed and are composed of large acini measuring 0.13 

 to 0.15 mm. long and 0.07 to 0.09 mm. wide. They occupy the greater 

 part of the substance of the clinging plug. The transverse vitelline 

 ducts, which could only be made out in sections, are short and the 

 vitelline reservoir is found between the two testes on the same side 

 as Laurer's canal. The terminal portion of the uterus, the vagina, 

 or metraterm, joins the male duct on the ventral side of the latter to 

 form a common passage leading to the genital opening which is sit- 

 uated somewhat dorsally in the posterior end of the body. Surround- 

 ing the opening are muscular fibers arranged in circular fashion, but 

 no well-developed genital sinus was seen. The large- thin-shelled 

 eggs are 0.130 to 0.146 mm. long by 0.089 to 0.097 mm. wide. They 

 are oval in shape, light-yellow in color and provided with an oper- 

 culum. 



The excretory system, as in other members of the Holostomata, 

 is in the form of a subcutaneous network of vessels and capillaries. 

 The excretory pore is small, located ventrally with respect to the 

 genital opening. 



Host. — Dog. 



Location. — Intestine. 



Locality collected. — China. 



Type specimens. — United States National Museum Helmintho- 

 logical Collections No. 18683, collected by Dr. R. T. Shields. 



Besides the type specimens of ProhemistomiLm indusfrium, the 

 United States National Museum Helminthological Collections (No. 



