PARASITIC WORMS BERMUDA. I. TREMATODES. 225 



cuticula in which, on the distal portion, are Hghtly embedded minute 

 spinelets. It is supphed with an outer sheet of circular muscle fibers 

 and an inner thicker sheet of longitudinal muscle fibers. Its lumen is 

 lined with cuticula. The external opening of the cirrus pouch is 

 separate from that of the metraterm, or vagina, and lies mesad to it 

 and to the left intestinal caecum. 



Female genitals. — The ovary (Figs. 13, 22) is a little larger than a 

 single testis and is irregular in outline with a lobed margin. It lies 

 at the right of the median plane, posterior to the uterus and at the level 

 of the most anterior testes. A short oviduct leaves the dorso-medial 

 portion of the ovary and, proceeding obliquely dorsad and to the left, 

 is joined by the Laurer's canal, whence it turns posteriad and mediad 

 across the dorsal surface of the shell-gland (gland of Mehlis) and is 

 joined in the central area of the shell-gland, by a duct from the yolk 

 reservoir. The common duct now enters the shell-gland and enlarges, 

 forming the ootype, which receives numerous small ducts from the 

 shell-gland, after which it passes ventrad and posteriad through the 

 shell-gland to its posterior margin, whence, after making several 

 coils, it turns cephalad along the left side of the shell-gland and con- 

 tinues as the uterus. The uterus makes its way cephalad, in the 

 median area, in wide compact transverse folds, which may extend 

 laterally as far as the outer edge of the intestinal caeca and vitelline 

 glands. The uterus terminates in a well defined metraterm, or 

 vagina, which opens to the exterior through a separate female genital 

 pore (Figs. 17, 20, 22) at the left of the male genital pore and ventral 

 to the left intestinal caecum. The metraterm is an elongated slightly 

 convoluted tubular organ, approximately as long as the cirrus pouch, 

 and lies caudad, and almost parallel, to the pouch. Its wall is strik- 

 ingly thick and muscular, being provided with a thick outer layer of 

 longitudinal muscle fibers and a thick inner (toward the lumen) layer 

 of circular fibers. Its lumen is lined with a thick layer of cuticula, 

 which is raised into longitudinal ridges. 



A compact, irregularly shaped, shell gland, or gland of Mehlis 

 (Figs. 13, 22), as large as the ovary, lies in the median field at the left 

 of, and more dorsal than, the ovary. A receptaculum seminis is not 

 present. A short Laurer's canal leaves the oviduct near the ovary 

 and proceeds dorsad and cephalad opening on the dorsal surface at 

 the right of the median line and slightly anterior to the shell-gland. 



The vitellarium (Fig. 22) is composed of two groups of vitelline 

 glands lying in the lateral fields of the third fourth of the body, ventral 

 to the intestinal caeca. Each group is made up of from seven to ten 



