ENTOZOA — TREMATODA. 
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acetabula porrecto, ore antico, simplice. The only species was dis- 
covered by Leuckart and Kollar on the branchiae of the Acipenser 
stellatus, Pall., and was called by the former Diplohothrium arma- 
tum. It has been specifically characterized ; — Corpore postice incras- 
sato ; rostro uncinato, uncis quatuor horrido ; acetabulis pedunculatis, 
lineatis, margine ciliatis, aculeo armatis. This worm has been already 
mentioned as ‘Diclibothrium crassicaudatum and armaHim (Wiener, 
Ann. 1. p. 82), and by Nordmann as Hexacotyle elegans (Lamarck, Hist. 
Nat. t. iii. 1840, p. 600). Leuckart does not allow the species Hexaco- 
tyle Thynni, Hexatliyridium pinguicola, Treutl., Blainv., and Hexa- 
hothrium appendiculatum, Kuh., Nordm., but reckons them with Poly- 
stomum. The Diplobothrium is distinguished from these Trematoda 
principally by the clasping-organs at the anterior end of the body. The 
reporter, in this respect, would rather agree with Nordmann’s view, and 
consider the acetabula also in Diplobothrium, as belonging to the after 
part of the body. If the two figures be compared which Leuckart has given 
of Diplobothrium armatum, and Octobothrium leptogaster, to be after- 
wards mentioned, a similarity in external appearance of the two worms 
will be obvious, except that the one has six and the other eight clasping- 
organs. In Diplobothrium, the part furnished with the six acetabula 
is the anterior end of the body. It must therefore strike us, that the 
same clasping apparatus, which in one animal is placed on the after 
part of the body, is, in another allied to it, on the fore part. The circum- 
stance, however, of Leuckart having seen a distinct opening on the point 
between the projecting clasping-organs, makes me hesitate in agreeing 
altogether with Nordmann ; on each side of this opening, considered 
by Leuckart as a mouth, are a couple of considerable horn-like hooks, 
directed backwards. Octobothrium lanceolatum has similar hooks at the 
end of the posterior part of the body. In Diplobothrium, behind these on 
each side, are three clasping-grooves, between which, the body elsewhere 
thin, is somewhat broader. In each groove is found a considerable number 
of fine white transverse strias ; and from the middle projects a white 
striated membrane, like a sort of valve ; each groove is also provided 
with a projecting clasping-apparatus-like claws. Of the inner organs, 
Leuckart has observed an intestinal pouch, simple at the beginning, 
and afterwards forked. The eggs, which were noticed in the opposite 
end of the body, had an oval shape and brown colour. Leuckart has 
characterized his genus Octobothrium thus; — Corpore molli, elongate, 
depresso ; apertura oris antica, infera, simplice ; acetabulis in utroque 
corporis partis posticas latere quatuor. — Leuckart refers Octobothrium 
merlangi, Nordm., to this genus also, although Nordmann has directed 
attention to the fact (Micograph. Beitrage, 1, p. 79), that this parasite 
has not eight acetabula, but only eight clasping-organs unprovided with 
an acetabular apparatus. The character of the genus will, therefore, 
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