Ccstode of the Genus Zschokkeella. 45 



The spherical egg-containing masses thus formed in the 

 interior of the segment are, without doubt, the homologues of 

 the multiple organs described by various authors in more or 

 less nearly related Cestodes, and variously termed " egg- 

 capsules," " Parenchymkapseln/' or " paruterine organs" 

 (Beddard, 1912). The manner of their formation, as seen in 

 the present species, appears closely similar to the process 

 described by Beddard (1912) for his species Inermicapsifer 

 capensis. There seems to be no ground for supposing that 

 the capsules in which the eggs are enclosed, whether they 

 are to be regarded as " paruterine organs " or not, are derived 

 in any way from the uterus. The evidence afforded by the 

 present species is entirely opposed to such a view. On the 

 contrary, it gives some support to the theory put forward by 

 Beddard (1912) that these egg-capsules are in reality multiple 

 " paruterine organs/'' not derived from the uterus, but from 

 the medullary parenchyme. 



In the paper referred to, Dr. Beddard devotes considerable 

 attention to these organs in Inermicapsifer, and seems 

 inclined to regard them as homologous with the similar 

 organs of Zschokkeella. He quotes v. Janicki (1910), who 

 describes the eggs in Zschokkeella as lying " einzeln in einfache 

 Bindegewebskapseln " (whereas several eggs are said to be 

 included in each capsule in Inermicapsifer), and uses the 

 supposed differences between their egg-capsules as a means 

 of separating the two genera. This mark of distinction, the 

 author states, he formerly believed to hold good ; but he 

 continues, " 1 do not, however, feel confident about this point, 

 and in view of other points of likeness between the genera 

 am disposed to compare more nearly the paruterine organs in 

 the two." 



While the present species seems to afford evidence in 

 support of this part of Dr. Beddard's views, it may be said, 

 at the same time, that it does not favour the theory suggested 

 in his paper (1914) on Rhabdometra cylindrica — that the 

 paruterine organ is not only not the derivative, but actually 

 the forerunner, of the uterus (loc. cit. p. 873, and text-fig. 9). 

 In the present case the uterus is well developed long before 

 there is any indication of the thickenings of the parenchyme 

 which are the beginnings of the egg-capsules. When these 

 thickenings appear the uterus simultaneously disappears. 

 Hence there can be — in this species, at all events — no question 

 of its being developed from them. 



Note on the Systematic Position of the Species. 

 At first sight I was inclined to place this form in the genus 



