ART. 10 HELMINTH PARASITES OF THE O'POSSUM — CHANDLER 7 



bottle-shaped structure, which ends at the level of the ovary. The 

 whole pouch is shaped very much like a crook-necked squash. The 

 duct inside the pouch undergoes an S-shaped loop in the posterior 

 portion of the pouch and is distended in one, or sometimes two, places 

 as a seminal vesicle. The distance from the genital pore to the other 

 end of the cirrus pouch is 1.25 mm to 1.55 mm, but, since the pouch 

 is bent or looped anteriorly, it is obviously somewhat larger than this. 

 The greatest width is 270ft to 360/a. The testes lie about in the middle 

 of the posterior portion of the body, in the posterior part of the cen- 

 tral field left free by the vitellaria ; they are rather irregular in shape, 

 and usually both are longer than broad, although the anterior one oc- 

 casionally measures about the same transversely as longitudinally. 

 The anterior testis measures 380|U, to 540ju, long by 290ju, to 395/>t, wide, 

 while the posterior one varies from 645ju, to 685/x. long by 290ju, to 380ju, 

 wide. They always lie in a somewhat tandem position. The ovary 

 lies just behind the end of the cirrus pouch; it is round or slightly 

 oval, and varies in size from 16T/x by 200/x to WOjx by 225/*. It is sep- 

 arated from the anterior testis by an irregularly shaped shell gland, 

 which is frequently tw^ice as large as the ovary. Slightl}^ anterior to 

 the ovary there is a seminal receptacle, usually about as large as the 

 ovary, but sometimes smaller. The vitelline glands consist of un- 

 usually large follicles; they occupy the entire body posterior to the 

 testes, broad lateral fields in the region of the reproductive glands, 

 and then narrow down and continue forward to about the level of the 

 posterior margin of the ventral sucker. The course of the uterus 

 could not be traced, but there is a large metraterm, which runs more 

 or less parallel with the outer curve of the cirrus pouch. Only 6 to 

 10 eggs are visible; these lie scattered in the region just anterior to 

 the ovary and alongside the posterior portion of the cirrus pouch. 

 They measure about 105/a to 110/* in length by about 60/* in width. 



Host. — Didelphis virglniana. 



Location. — Small intestine. 



Locality. — Houston, Tex. 



Tyye specimen. — U.S.N.IM. Helm. Coll. No. 8547; paratype. No. 

 8548. 



Remarks. — Three species of the genus Rhopalias., all from South 

 American opossums, have hitherto been described, namely, R. 

 coronatus (Kudolphi, 1819), R. Icorridus (Diesing, 1850), and R. 

 haculifer Braun, 1901. An undescribed species of the genus has been 

 recorded by Dikmans (1931) from opossums in Louisiana. The 

 genus and its species have been very well reviewed by Braun (1901). 

 The internal anatomy of all the species is much the same, but the 

 species differ markedly in size, proportions of anterior and posterior 



