MR. R. OWEN ON THE ANATOMY OF DISTOMA CLAVATUM. 383 
almost cartilaginous texture at the bottom, which is perforated by a minute orifice, 
through which the fluids absorbed from the animal infested by the Distoma pass into 
the digestive tubes ; these are two in number, and are continued, slightly enlarging and 
diverging from one another, to the cells at the posterior part of the body. 
About 2 lines’ distance from the mouth, on the concave side of the neck or narrow 
part of the body, there is a small transverse slit, concealed by the wrinkles of the in- 
tegument, forming the outlet of the generative organs. The large cavity behind this 
slit is simply for adhesion, and does not communicate with the interior of the body: 
it is provided with a strong muscular concave disc, the margin of which is papillose ; 
and external to the papille it is surrounded by a circular fold of the integument. ‘The 
body continues to enlarge behind the acetabulum, and terminates in an obtuse clavate 
extremity. On closely inspecting this part a minute central orifice was clearly per- 
ceived, which conducted to a narrow cavity formed between two layers of a villous 
membrane, extending vertically across the terminal dilated part of the animal. No 
communication could be detected, upon the most minute inspection, between this cavity 
and the rest of the body. 
Besides the cellular parenchyma, of which the body is chiefly composed, the three 
systems of canals, digestive, vascular, and generative, which the Trematoda usually 
possess, are present in their ordinary forms and positions ; the cells at the smaller end 
of the body were occupied, in this specimen, by a yellow fluid, containing numerous 
ovula of the same colour, many of which had thence passed into the tortuous oviduct. 
Towards the posterior part of the body the cells enlarge in size, and are principally 
transverse in their direction. 
The clavate end of the body is occupied by two large lateral cavities in addition to 
the mesial one above mentioned. The side cavities were filled with a dark brown fluid, 
containing minute opake particles of the same colour, similar in appearance to partly 
digested blood. The internal surface of these cavities is of a black colour, and covered 
with minute folds and wavy wrinkles. The dark-coloured canals which meander over 
the lateral parietes of the body take their origin from these large cavities, which also 
communicate with the smaller canals anterior to them, and from them they receive the 
nutriment, which is carried backwards by the two alimentary canals from the mouth ; 
so that they hold an intermediate position between the alimentary and the sanguiferous 
canals. Analogous reservoirs have been observed in Amphistoma conicum, in which 
they have been denominated by Laurer cisterna chyli ; and similar cavities are also termed 
chyle receptacles (Chylusbehélter) by Nordmann! in the minute Trematode parasites which 
he has detected in the eyes of Fishes. In the Distoma clavatum, however, these receptacles 
have no communication with the mesial cavity or the posterior aperture. Nordmann 
observed that a white fluid was ejected by successive spasmodic actions from the posterior 
aperture of Diplostomum volvens, which corresponds to the one above described in Di- 
1 « Am hintern Ende dieses birnférmigen Organs befindet sich eine deutliche, trichterférmige Offnung, die 
durch einen Sphincter geschlossen werden kann. Man kénnte es vielleicht am besten mit dem Namen eines 
Chylusbehiilters bezeichnen.”—Micrograph. Beitrige, p. 38, Hft. 1. 
352 
