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REPORT ON ZOOLOGY, MDCCCXLII : 
into two side-branclies, which stretch to the end of the after part of the 
body. He considers this organ as the liver, and conjectures, that the 
intestinal canal, formed conformably to it, is situated under it. The 
reporter would here add, by way of explanation, that this series of 
cells is the intestine not yet completely developed, and that it after- 
wards loses all this cellular appearance, and then represents a closely- 
bounded, forked, blind canal. Steenstrup observed two spiral organs 
running along both sides of the anterior part of the body, and disap- 
pearing in the neighbourhood of the abdominal acetabulum. He does 
not give any opinion on the use of these lateml canals, which form at 
the same time a ring round the pharyngeal tube. The reporter has also 
observed them, and discovered their blind terminations near the abdo- 
minal acetabulum ; they also appeared to him to discharge themselves 
into the bottom of the acetabulum of the mouth, so that they may perhaps 
be compared to a salivary gland, or some other organ of secretion, e. g. 
a spinning or a poisonous organ. These side- vessels do not form meshes ; 
and if Steenstrup has seen them, they must have been meshes of blood- 
vessels, which are present in all fully-formed Trematoda, and at times 
can be distinctly observed in the larva of many Cercarice. Another 
organ, which passes along the body from beneath, with two lateral 
branches, is the excrementary organ, and must not be confounded with 
the anterior lateral vessels. When the Cercarice have arrived at the 
point of becoming pupse, they progress so rapidly, that they do not wait 
till they have penetrated the body of the snail which they have 
selected for their future abode, but pass into the state of pupae upon the 
cuticle. Up to this period the habits of Cercarice have been long 
known; but Steenstrup has followed them farther. In the state of 
pupae they remain long in an unaltered condition ; after several months 
he found them still the same, while the anterior end of the body became 
covered by a number of small-pointed prickles. He saw such indivi- 
duals free in the parenchyma of the snail. Some had still a wreath of 
spines at the mouth, others had lost it, but in all the intestinal canal 
was very much dilated. The pore visible at the upper end of the oeso- 
phagus, mentioned by Steenstrup, can only be the head of the pha- 
rynx, which does not always lie close in the acetabulum of the mouth, 
but is sometimes observed at a distance from it. The organs, which 
he saw filled with little balls on both sides of the body, above the abdo- 
minal acetabulum (tab. ii. fig. 8, e. and 8 f.), are the superior blind ends 
of the excrementary organ. Thus far Steenstrup’s direct observation 
of the metamorphosis of the Cercaria echinata extend. How the 
small Distomum which comes from this Cercaria farther developes 
itself, he infers only from analogy with other Trematoda, which in 
the perfect state produce a brood of young, resembling Infusoria. From 
these young, then, as is shown by the observations of Bauer, Bojanus, 
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