524 JOSEPH STAPFORD, 



it again turns obliquely forwards and to the left. There are then, so 

 far, three bends giving four portions of the tube side by side. At 

 the third bend, pointing backwards, is given off a canal which extends 

 in a straight, slightly u])ward course to near the posterior end of the 

 animal where between the blind end of the intestine and the point of 

 union of the large excretory vessels it swells to a thickened sack. 

 This is the Laurer's canal to which we shall later return. Following 

 from the origin of this canal along the fourth portion of the zig-zag- 

 formed ovary and duct we find a second adjunct to the main con- 

 ducting tube. This is the unpaired vitelline duct (Fig. 16 wF) 

 which when followed a short distance exi)ands into a triangular cavity 

 — the vitelline reservoir. From the two outer angles of this 

 proceed two side canals, the paired transverse vitelline ducts, 

 which turn upwards through the diaphragm and join two lateral longi- 

 tudinal canals. The latter bear on their sides the follicles (Fig. 16^ 

 25 ÄD, FV) of the vitelline glands. Returning again to the main 

 course and following it a distance from the opening of the vitelline 

 duct equal to the length lying between the latter and the Laurer's 

 canal one finds at the entrance to a slight widening of the tube per- 

 haps a few strongly refracting drops and from this point radiations 

 in the surrounding triangular-shaped shell gland (Fig. 16, 12 SD). 

 The widened continuation of the canal is the ootype. All the parts 

 of the main canal up to this point lie pretty nearly in the transverse 

 diameter of the infra-septal body portion of the animal the bendings 

 being approximately back and forwards. The shell-gland and ootype 

 balance on the left side against the ovary on the right. From the 

 ootype with its slightly constricted ends the oviduct passes into another 

 widening caused by an enormous aggregation of spermatozoa. Such 

 an assemblage of sperm is found to be general among Trematodes 

 and this portion of the oviduct is designated by Looss recepta- 

 culum seminis uterinum. From here onwards the oviduct con- 

 tinues as a simple, uniformly constructed, long canal which may fold 

 back and forwards, or sideways until, having passed round the end 

 of the septum, and having made numerous transverse folds above the 

 intestine, it approaches the front end of the animal and expands into 

 the muscular vagina. In living animals the relative positions of 

 the parts succeeding to the opening of the Laurer's canal are often 

 very different as might be expected but Laurer's canal and oviduct 

 always lie between the two transverse vitelline ducts. 



The ovary measures 0,35 mm long, from the blind end to the 



