284 ON MOREAUIA MlJRABILIS, 



Relationships. —Amongst known Trematodes, Hapalotrenia 

 Looss(5, 6), and Liolope Cohn(2, 8), seem to approach most nearly 

 to Moreauia in the essentials of their structure, in spite of the 

 great difference in form and general appearance. The main 

 differences in the form and position of the various organs, which 

 are of primary importance in deciding the relationships of those 

 two gfenera on the one hand, and Moreauia on the other, are, 

 after all, mainly due to the remarkable extent to which the body 

 of Moreauia is broadened out at the expense of its length. 



In Hapalotrenna (Fig. 2), we have a worm with large testes 

 (divided up into a number of separate lobes) placed in a line, one 

 behind the other, with the ovary between. The yolk-glands, 

 consisting of a large number of comparatively small follicles, 

 occupy the whole lateral field behind the ventral sucker and out- 

 side the intestinal limbs, encroaching also to a slight extent on 

 the space to the inner side of those limbs. The genital opening, 

 with the cirrus-sac and vagina, is on the left side. The excretory 

 vesicle is essentially Y-shaped. Is'ow, if we imagine a worm like 

 Uapalotrema to begin to extend laterally, right and left, the 

 excretory vesicle and pore remaining in the middle of the pos- 

 terior end, and the genital opening remaining near the middle of 

 the left side till a shape of body similar to Moreauia is reached, 

 we should have a worm very like Moreauia in its external 

 features, provided that the lateral extension on the right side 

 took place in such a way that the testes remained in a line 

 parallel with their long axes, with the ovary between. And in 

 such a spreading out, in order that room might be found for two 

 such large bodies as these testes, this would naturally have to 

 be the case. 



After such a transformation in shape, we should have a worm 

 in which the configuration of the intestine would be essentially 

 the same as that present in Moreauia\ the excretory vesicle 

 would be very similar, the lateral stretching producing the slight 

 dilatation of the upper limb of the Y seen in Moreauia) the 

 large, elongated, very deeply lobed testes, with the ovary be- 

 tween, would correspond with those of Moreauia in form and 

 position, though the testes of the latter are less deeply lobed; the 



