876 DR. V. E. BEDDAIID ON 



111 many of the egg-follicles the form of the entire follicle is, as 

 already stated, oval. In these cases, which axe illustrated in text- 

 fig. 149, the layer of cells extends at the two poles of the ellipse 

 for a considerable distance outwards, and thus a heap of cells is 

 formed. These masses of cells generally enclose a distinct cavity, 

 the function of which arrangement may be to protect the egg 

 from the efl'ect of pressure due to contortions of the worm's body. 

 In any case we have here a state of affairs very unlike that of 

 Eugonodceum. It appears to me to be very possible to make a 

 comparison between the egg'-sacs of Oochoristica and the cor- 

 responding structures in two species of Davainea stiidied by 

 V. Janicki*. Referi'ing, for example, to fig. 9 of his memoir, the 

 space lying between the two " Embiyonalhiille " at the poles 

 of the elongated embiyo might well coi'respond to the cavity 

 which I describe and figure here in Oochoristica. But this com- 

 parison, which may be carried a good deal further, is not germane 

 to the object of my present communication, which is to compare 

 Eugonoclmum with other allied genera. 



§ General Observations. 



On the whole the characters of the present species ally it most 

 nearly to the genus Ilonopylidium, the alliance being ver}^ largely 

 due to one species only of that genus, viz. Ifonopi/Udium rostel- 

 latum. The genns MonopylidiuTn is thus defined by Ransom f:— 



(1) Rostellum armed with a double or single crown of hooks. 



(2) A single set of reproductive organs in each segment. 



(3) Genital pores irregularly alternate, rarely unilateral. 



(4) Genital canals pass between the longitudinal excretory 



vessels and dorsal of the longitudinal nerve, or dorsal of 

 both excretory vessels. 



(5) Testicles numerous (20 to 40 or more), behind the female 



glands or, also, on both sides of the latter. 



(6) Vas deferens coiled, seminal vesicle absent. 



(7) Uterus breaks down into egg-capsules, each containing one 



or several eggs. 



The worm which forms the subject of the present jDaper differs 

 from Monopylidium in JSTos. (1) and (7), and agrees with the 

 genus in the other- characters set forth. These differences appear 

 to be quite enough for- generic separation were it not for the 

 structui-e of Alonopylidium rosiellatum. This species has no 

 rostellar hookSj and of the uterus or rather the disposition of the 

 ripe eggs Pi-of . Fuhrmann writes % : " Les oncospheres se trouvent 

 reparties dans tout le parenchyme : chacrrne d'elles est entouree 



* " Ueber zwei iieue Arten des Genus Davainea," Arch, de Parasitologie, vi. 1902, 

 p. 257. 



t Bull. U.S. Nat. Mus. No. 69, 1909, p. 76. 



X "Nouveaux taeuias d'Oiseau.x," Rev. Suisse Zool. xvi. 1908, p. 65. 



