ON A NEW REPTILIAN CESTODE. 109 



travels inwards for some distance at right angles to the 

 long axis of the segment and then curves backwards so as 

 to lie along the midline, and passes dorsally over the com- 

 mon oviduct. It becomes slightly enlarged to form a 

 receptaculum seminis just behind the ovarian " bridge. " 

 The vagina now becomes the fertilising duct and passes 

 backwards for a short distance after taking up the common 

 oviduct. Fertilisation of the ova takes place here. The 

 vitelline ducts from the laterally situated vitellaria probably 

 now join it just as it bends round to lie ventrally to its 

 earlier course. Its walls now penetrate the shell gland, a 

 small and inconspicuous organ lying just behind the ovarian 

 bridge. This fertilising canal now passes forwards below 

 the ovary as the uterus. Thus the ovarian bridge or oviduct 

 lies between the vagina (dorsal) and the uterus (ventral). 



In some segments, the vagina opens just in front of the 

 cirrus sacs, passes inwards beside it and curves round its 

 inner edge below the vas deferens to occupy its normal 

 course along the middle of the segment. Its position in 

 transverse section is indicated in fig. 4. 



The vitellaria consist of two masses situated in an elon- 

 gate series in the cortex just externally to each longitudinal 

 excretory vessel. Each group extends from near the 

 anterior end to near the posterior end of the mature seg- 

 ments. They are hardly recognisable until the vas deferens 

 has become strongly coiled. The individual follicles are 

 very small and numerous, measuring about seven micra in 

 diameter. They are irregularly rounded or elliptical. 

 Probably the vitelline ducts pass inwards posteriorly to the 

 ovarian lobes and then unite to pass forwards to the 

 fertilising ducts. The vitellaria are not represented in the 

 figures. 



The uterus is a thin- walled, long, simple tube lying just 

 below the vagina along the middle of the proglottid and 



