64 Proceedings of the Royal Irish Academy. 



six times the length of the entire body (not ten times as in P. multi- 

 einctum). This tube, like the uterus, is transparent, whitish when 

 empty or faintly cream-coloured when filled with eggs, contrasting 

 thus strongly in colour with the dark brown digestive tract. It has a 

 thin basement layer, a very thin muscular coat of mixed circular and 

 longitudinal fibres, not in separate laminae, and these fibres are striped 

 (not smooth as Harley found them in P. multicinctum). The tortuous 

 tube in some of the females was so full of e^gs as to distend the entire 

 body, so that on a section being made, the whole perivisceral cavity 

 appeared full of eggs. In one specimen, at least 16,500 eggs 

 existed . 



The tortuous oviduct, when traced back to its origin, begins as a 

 fine tube attached to the medio-ventral wall of the body ; at the second 

 distinct ring behind the mouth, and on each side of it, is a roundly 

 ovate sac, full of spermatozoa and granules. The former, are arranged 

 in bundles or spermaphores, but with no traces of thickened cases. 

 These sacs have a thin proper wall, and open directly into the oviduct 

 at its commencement. This commencement is I'eally the point of coa- 

 lescence of two fine tubes ; the ovarian tubes, which arise from the 

 cephalic end of the ovary, and running a short course, end by uniting 

 between the ovate receptacuJa seminis to form the oviduct. The ovarj^ 

 is a thick-walled single tubular gland, extending from near the tail to 

 the head, containing material which posteriorly appears simply granular, 

 but which nearer the ducts becomes more ditferentiated into rounded 

 or oval masses attached to a central axis. 



The smaller males have a still more highly complicated apparatus. 

 This organ consists of a large bilobate testis stretching on the dorsal 

 wall of the body cavity as far as the tail, and lying over the alimentary 

 canal. Its duct or vas deferens appears at the upper end of the gland, 

 runs backward towards the tail for a very short extent, and then turns 

 forwards again looping under the duct of one of the accessory glands. 

 The vas deferens then divides into two lateral branches, right and left, 

 which pass outwards and forwards, each ending in an intromittent 

 organ. The divided extremity of the vas deferens is known as the 

 annular canal whose relation can be seen in Plate 2, fig. 6. Into each 

 limb of the annular canal posterioi'ly there opens an accessory gland. 

 These are long, tortuous, tubular glands placed one on the right and 

 one' on the left, veutrad of the testis, thick-walled and lying one on each 

 side of the vas deferens. The right of these crosses over the loop of the 

 vas. These glands secrete the glutinous material which unites the 

 filamentary spermatozoa into spermaphore clusters. The concavity in 

 front of the annular canal is occupied by two lateral elliptical pouches, 

 contiguous in the mesial line, lying under the digestive tract, and 

 opening on the surface ventrally in front ; these are the cirrus pouches 

 which contain the intromittent organs. These are tubular, the pro- 

 longed extremities of the vasa deferentia, and are nearly equal in length 

 to half the animal's body. Each of these having preserved a uniform 

 calibre for most of its extent, ends by suddenly dilating, then narrow- 



