ENTOZOA — CESTOIDEA. 
313 
where to classify, has been described and figured by Rathke, under the 
name of Peltog aster ]^aguri (Neuest. Danz. Schr. Bd. iii. Hft. 4, p. 105). 
The animal lives on the abdomen of the body of the Pagurus hern- 
hardus, is 6'" in length, and forms an elongated arched crooked oval, 
the thicker end of which passes into a short wide tube ; the margin of 
the aperture of this tube, which is the mouth of the animal, appears 
padded and somewhat undulated. Cirri and eyes are wanting, the epi- 
dermis is thick and colourless, and in the middle of the body there is an 
abdominal acetabulum, in the form of an amber-yellow radiated emarginate 
shield of a horny texture, on a horny longitudinal stripe. The presence 
of this acetabulum, with which the parasite is fastened to the body of the 
crab, induced Rathke to reckon it with the Trematoda. Through the 
mouth we arrive at a very wide intestinal pouch, which reaches to the 
end of the body, and is every where fastened to its walls by cellular 
tissue. The worm does not prey upon the juices of the Pagurus, but 
sucks the nourishment which is conveyed to it out of the water. The 
intestinal pouch serves also for hatching the eggs. In young indivi- 
duals, the inner surface of the pouch, towards the back, is covered with 
soft flat masses of fibres ; in older ones these spots are occupied by some 
layers of eggs, which are united to each other, and with the intestinal 
pouch, by a transparent firm substance (a hardened secretion) ; the eggs 
contain oily drops of a copper-red colour. The ovaries are situated 
between the abdominal wall of the body and the intestine, in the form 
of two pouches, which are divided into departments by transverse walls, 
and, when swollen with eggs, fill out the whole body. Somewhat behind 
the middle of the body, a short narrow canal projects from each ovary, 
and opens into the intestine. Before these openings two others are 
found, which lead to two warty elevations of the alimentary pouch, 
probably organs of attachment for the eggs. No nervous system was 
discovered. 
CESTOIDEA. 
Mayer has discovered, outside the thin intestine of a Testudo my das, a 
great number of small greyish-white knots, of f of a line in diameter, 
(Miill. Arch. a. a. O. p. 213. They consisted of a husk, lying under the 
peritonasum, with cheesy contents, between which a clear oval little 
bladder, of I'" in size, with an Entozoon, was concealed. This latter 
had an oval form, and was stronger at the one end, at the other more 
slight and bent inwards. The animal was composed of an external layer 
of balls and bladders, and an internal finely granulated layer, in which 
four cord-formed sheaths lay close beside each other. These contained 
four probosces, sown over with unequal teeth, which, on the lively 
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