258 Mr. W. H. Leigh-Sharpe on 
The parasites reposed in the body-cavity of the worm, in 
segments 10 and 11, all but one diploid being on the host’s 
right side. ‘They appeared of an opaque china-white colour, 
the largest (fig. 1, A) being 5 mm. in length, the others 
4mm. All were laterally bowed in shape, and curved round 
the cesopliagus of the worm between the calciferous glands 
and the pouch, but attached by their anterior extremities to 
the seminal funnels. The worm had been killed an hour and 
a half previous to dissection by immersion in methylated 
alcohol, and none of the parasites showed any sign of life. 
It is remarkable that such a large number of parasites 
should occur within one host, and curious that here we have 
two individuals permanently associating as one, though not 
conjugating. 
Monocystis agilis. ‘Two conjugants in polar apposition. 
N., nucleus. 
The unique presumed conjugation of Monocystis magna, 
Schmidt, has been described by Cuénot (1900) alone, who 
gives a figure which, to my mind, is not as satisfactory as 
might be, since it shows the supposed conjugants so clearly 
as two separate individuals, instead of being apposed in such 
a way as to look like one individual (fig. 1), the lines of 
demarcation between them superficially resembling the 
alimentary canal of some single animal. The association in 
this species alone was said to be longitudinal—a fact which 
appears to have been known at the earliest to Bosanquet 
(1894), who mentions it casually in describing another 
species, and even admits en passant into his paper a very 
