ENTOZOA — TREMATODA. 
303 
That Steenstrup found small Echinorhynchi within separate capsules 
on the mesentery, liver, and intestine of a plaice, is a new voucher in 
proof of the nomade habit of these animals. 
TREMATODA. 
Creplin has described a new Monostommn (M. eocpansum), from the 
upper portion of the small intestine of a river-eagle (Flussadlers), which 
is distinguished by the fore-part of the body being extraordinarily 
flattened and broad (Arch. 1842, i. p. 327). In the broad part Creplin 
observed an organ composed of granular balls ; the very small mouth had 
an acetabulum, and a still smaller pharynx, from which the oesophagus 
ran to the middle of the anterior part of the body ; from this spot, on each 
side, an intestine went down to the end of the hinder part. Two vascular 
trunks stretching down on the inner side of the intestinal tubes, which, 
in one specimen, contained in some places white coagulated masses, are 
perhaps the organs of excretion that discharge posteriorly, and which 
the reporter has met with in different Monostoma. The dendritic 
ovaries begin in the latter half of the flat fore-part of the body, and 
stretch on both sides to the extremity. The wide uterine canal, the 
commencement of which Creplin could not find, runs with many wind- 
ings through the anterior half of the hinder part of the body ; the end of 
the uterus must perforate a pear-shaped white knot in the posterior 
margin of the body, and then open externally on the middle of the 
abdominal side. The brown eggs of the uterus are pretty large, oval, 
with a small knot at the narrowed end. The two testes, lying behind 
each other in the posterior part of the body, have very deep indenta- 
tions, by which they seem divided into radiated, or fan-shaped branches. 
Creplin could trace only one vas deferens, and that from the posterior 
testis : it passed into two spiral seminal receptacles before it ended 
in the receptaculum cirri. It is to be lamented, that this extremely flat 
worm could not be examined when alive. 
Monostomum mutabile has been figured by Leuckart (Zool. Bruchst. 
op. ant. cit. iii. p. 35), with the remark, that Nitzsch had sent him, 
under the name of Monostomum aspersum, a parasite from the nasal 
sinus of Anas fuligula, which was very nearly allied to the Mon. fiavum 
of Mehlis. 
Mayer has recognised flickering movements in the vascular system of 
Amphistomum subclavatum (Neue Untersuch. ant. cit. p. 24). The 
black balls which Mayer saw in canals, forming an arch at the posterior 
part of the body, and considered as ovula, or yolk, are the excrements 
of the excreting organ of this worm, which discharges at the hinder part 
347 
