218 MR. F. E. BEDDARD ON A 



text-figure 30. Clerc also figures somewhat similar changes 

 in the uterus of a species of Dilejns * (not named), where the 

 scattered ova actually penetrate the cortical parenchyma. This 

 fact I have also observed in Otiditcenia. 



There are, therefore, clearly difierences of importance between 

 the ultimate fate of the uterus in the two genera — as I regard 

 them — Monopylidium and Otiditcenia. In the former the eggs 

 are in most (? in all) species finally scattered through the paren- 

 chyma unaccompanied by any other cells such as occur with the 

 ova in Otiditcenia, in which genus the eggs are at the very 

 end grouped into many more or less isolated but not well-marked 

 capsules. There remains a comparison of the uterus of Otiditcenia 

 with that of Davcdnea. With regard to certain species of the 

 latter there is no particular comparison possible. But Olerc has 

 figured the egg-capsules of Davainectfrontina'f, which do seem to 

 present certain similarities to the egg-capsules of Otiditcenia 

 eupodotidis. In the former worm the egg-capsules differ from 

 those of such a species as D. comitatus % in that the individual 

 eggs do not lie closely together within the capsule, but are more 

 or less widely separated with a good deal of interstitial matter 

 between them, which the author regards as a part of the medullary 

 parenchyma which has undergone alteration. This and the 

 enclosed eggs is surrounded by a definite layer of cells, which are 

 not to be looked upon as a part of the persisting walls of the 

 uterus, since in that case they would not enclose a portion of the 

 medullary parenchyma. If this interpretation of the facts be 

 correct, there is clearly no possible correspondence with the 

 phenomena which I myself describe in the present paper. It 

 seems to me, however, to be not impossible that the supposed 

 altered parenchyma-cells which lie amongst the ova are really the 

 equivalents of the similarly placed cells in my genus Otiditcenia. 

 Moreover, Ransom § speaks of cells accompanying the scattered 

 ova of Davainea rliynchota. 



I am disposed, however, to think that there is another view to 

 be taken of the egg-capsules of Davainea frontina , as figured by 

 Olerc. From the account that he gives of them in the text and 

 of the investigations of others on the same subject — to which we 

 may add those of Leuckart || — it seems clear that the egg-capsules 

 correspond to the paruterine organs of a genus recently described 

 by myself % under the name of Thysanotmnia, as I have already 

 suggested. In this case we cannot agree with the statement of 

 Ransom, in defining the subfamily Davaineinse, that the " uterus 

 breaks down into numerous egg-capsules." For in Thysanotcenia 

 there is, I think, no doubt that the cases in which the eggs finally 

 come to lie have nothing whatever to do with the uterus, and are, 



* Clerc, loc. cit. pi. xi. figs. 75, 76. 

 t Loc. cit. pi. xi. fig. 80. 



t Ransom, Bull. U.S. Nat. Mus. no. 69, p. 17, fig. 8, cap. 

 § Loc. cit. p. 14. 



II Quoted in Bronn's ' Thien-eichs,' p. 1445. 

 it P. Z. S. 1911, p. 1000. 



