568 BR. F, E. BEDDARD ON 



the definition of this genus by Ransom *, that he regards these 

 spaces a,s disjected portions of a pre-existing viteras. It seems 

 clear, from the illustrations given by Mola t, that the egg-holding 

 cavities are not lined by cells in Tcenia marcJiali (a species which 

 Fuhrmann refers to the genus Monopylidmni), and in this fact 

 we find an agreement with the two tapeworms described in the 

 present paper. A very remarkable condition is described and 

 figured by Fuhrmann + in Monopylklhmi rostellatum. In this 

 species the eggs are scattered singly th:^jough the medullary region, 

 and each egg fits closely into a hexagonal mass of delicate tissue, 

 which itself fits equally closely into the medullary parenchyma, 

 leaving no gaps or spaces anywhere. It seems to me to be just 

 possible that this " parenchyma vacuolaire " which immediately 

 surrounds the egg may be simply the outer egg shell, which 

 I have myself observed in Di2)lo2)ylidmm, when crumpled, to 

 present quite the appearance of a retiform tissue. It is finally 

 to be noted that the disposition of the mature ova in Diplo- 

 pyliclium is perhaps also to be compared to the scattering of the 

 eggs in Inermiccqjsifer capensis § befoi-e the inclusion of these in 

 the parenchymal organs. But it must always be borne in mind 

 that in the case of Diplopylidium., Oochoristica, and Monopylidium, 

 completely mature j^roglottids may not j^et have been seen. A 

 final stage may be the formation of paruterine organs, though 

 this does not seem to be very likely. 



We may characterise this new form as follows : — Size small, np 

 to 6 mm. ; number of segments up to 28. Scolex with retractile 

 muscular rostelhim armed with two rows of hooks, 17 in each 

 row. Suckers unarmed. Neck short ; posterior j^roglottids two 

 or three times as long as broad. They do not project posteriorly 

 or overlap. Generative orifices lateral and paired in each pro- 

 glottid, opening at or i-ather in front of the middle of the 

 proglottid. The ducts pass between the longitudinal water- 

 vascular tubes. The female orifice is situated in fi'ont of the 

 male. The water-vascular tubes are two on each side, the dorsal 

 being of narrower calibre ; they are placed one above the other. 

 A longitudinal muscular layer, only a few fibres thick, separates 

 the cortical and medullary regions. The testes az'e numerous and 

 large, filling up all the proglottid not occupied by other parts of 

 the generative system ; testes disappear in posterior proglottids 

 when egg-chambers appear. The cirrus-sac is large, with muscular 

 walls, not lying in one straight line, but bent backwards in rela- 

 tion to the fact that there are two in each proglottid. The cirrus 

 is very slender and coiled within its cirrus-sa,c. The sperm-duet 

 is coiled and lies on each side in front of cirrus-sac. Ovaries 

 distinctly paired in each proglottid, lying laterally behind the 



* " The Tgenioid Cestodes of N. American Birds," Bull. U.S. Nat. Mus. no. 69, 

 1909, p. 76 : " Uterus breaks down into egg-capsules." 

 t Bull. R. Ac. Belg. 1907, p. 806. 



J " Nouveaux tienias d'Oiseaux," Rev. Suisse Zool. xvi. 1908. 

 P. Z. S. 1912, p. 586, text-fig. 76. 



