STUDIES ON THE DIGENBKTIC TREMATODES. 435 
The lining epithelium appears to be of somewhat lower type, 
and the muscle-layers are rather finer. 
From the posterior end of the vesicula seminalis a single 
vas deferens, ‘023 mm. in diameter, passes backwards to the 
level of the middle of the ovary, where it divides into the 
paired vasa. These remain close together for a short distance 
and then separate to enclose the ootype. They join the 
testes on their dorsal surface. 
The testes are median, close together, and directly behind 
each other. They occupy almost completely the middle third 
of the body, the posterior testis being exactly one third from 
the posterior end of the body, and the anterior testis a slightly 
greater distance from the anterior end. Lach has a rather 
peculiar shape, differing from that of the other. The anterior 
testis is twice as broad as it is long, and its thickness equals 
its length. It is therefore much compressed in the long axis 
of the body ; not only so, but there is a distinct hollowing 
out both on the anterior and posterior surfaces, which is 
obvious only on longitudinal section. It consists of four 
lobes, two large lateral with small anterior and posterior 
lobes. The posterior testis is much more symmetrical, being 
composed of four nearly equal lobes—an anterior, a posterior, 
and two lateral. The anterior lobe is slightly indented on 
its ventral aspect, and the posterior shows one or two 
irregularities, but the lateral lobes are almost uniformly 
rounded. ‘The lobing is quite deep, and the central part of 
the testis is about equal in size to each of the lobes. This 
testis is almost iso-diametric, and its maximum thickness is 
about half its diameter. ‘he thickness diminishes from the 
centre to the periphery. This symmetrical shape might be 
regarded as the normal condition of the testes, and the shape 
of the anterior testis as the result of deformity. In Braun’s 
figure (fig. 3) the testes are shown as irregularly four-lobed 
bodies. The particularly long posterior lobe of the hinder 
testis, to which Braun draws attention, is evidently not a 
constant feature. In Br. palliatum the testes are lobed, 
but the lobes are smaller, more numerous, and do not appear 
