555 
half the length of the body. A very short median tube passing forward 
from the excretory pore very soon broadens into the common meeting 
place of two broad and much flattened bladders. These lie dorsally to 
the coils of the uterus. The remainig members of this system have not 
yet been recognized. 
The testes lie in the level of the middle of the body and opposite 
each other. There is a long and narrow cirrus sack, on the left side of 
the body, whose posterior end lodges the seminal vesicle which is filled 
with spermatozoa and passes into the ejaculatory duct. The ovary lies 
between the testes and nearer the right one. It is somewhat pyramidal 
in form the base lobed and the apex looking backward and inward where 
the short oviduct originates. Laurer’s canal, a small seminal receptacle 
and the duct from the vitellaria open into the oviduct as it passes through 
the shell gland whose cells are well developed and arranged radially 
about the duct. Laurer’s canal opens to the exterior in the centre of 
the dorsal surface in the plane of the ventral sucker. The uterus may 
be divided into two parts. The proximal part lies wholly on the left 
side and consists of several loops which, in the main, run longitudinally. 
The uterus then crosses to the opposite side, to which the second part is 
confined, the coils again running chiefly longitudinally until at last the 
tube crosses under the ovary to enter the metraterm, which lies on the 
left side internally to the ejaculatory duct. 
Earlier writers (e. g. Braun 1893 p. 737) on trematode structure 
state that the body wall is infolded at the genital opening to line the 
genital atrium retaining its structure with the exception of the spines. 
In the case of L. arcanum however the spines follow the cuticle into 
the atrium and clothe its surface densely everywhere. In addition to 
this spines are found in the outer parts of both the ejaculatory duct 
and the metraterm which are as large and as denseas those on the outer 
surface of the body. The lining of these organs still more deeply chan- 
ges to a layer of fine, villus-like papillae packed very closely. These 
papillae possess the same optical properties as the cuticle and are un- 
doubtedly chemically the same substance. They are elongate, slender, 
bluntish projections from the wall standing very close together. The 
centre of each one of these is occupied by a spine similar in form and 
appearance to those of the cuticle. These spines show the same strong 
affinity for iron-haematoxylin as the outer spines, so that this part of the 
coat is very conspicuous in sections and looks very different from the lin- 
ing of these passages in most trematodes. The details of form of these 
papillae and their central spines were clearly seen in sections of the 
papillae in different planes. A detailed account of them will be published 
later. 
