318 
REPORT ON ZOOLOGY, MDCCCXLII : 
PSEUDO -HELMINTHES. 
Mayer has given his views on the nature of the Spermatozoa, and is 
still convinced that they are actually animals, as their peculiar form and 
organization, as well as their voluntary movements, correspond to the 
animal character (Neue Untersuch. p. 9). 
Krohn has shown that the Vertumnus thetidicola, Otto, which, for a 
long while, has been held as a Trematoda~l\ke parasite, is not an inde- 
pendent animal ; but that it is constituted from forms which are only 
appendages of the Thetys, but have certainly a frail connection with it 
(Miill. Arch. 1842, p. 418). The reporter perceives, from the Transac- 
tions of the Meeting of Naturalists at Turin, that already, in 1840, 
Verani had questioned whether these appendices of the Thetys were 
pseudo-parasites (Isis, 1842, p. 252), and that Nardo had remarked, 
that the Thetys was able to reproduce them when torn otF. It fol- 
lows, therefore, that the remark of Maori, made many years ago, who 
had correctly understood the meaning of these appendices, must be again 
added to the description of Thetys leporina, viz. : — Majores appendices 
sunt membranaceae, ovato-oblongae, acutae, deciduce (Atti della reale 
academia della Scienze di Napoli. Vol. ii. 1778, p. 170, tab. 4.) Krohn 
has distinctly perceived the skin of the Thetys to pass over, without 
interruption, the parts which have been named Vertumni; and that 
the same colour which the Thetys itself has, is found again on the ap- 
pendices. The observations of the reporter agree completely, in the 
latter respect, with Krohn’s assertions. He may add also, that one 
sees, on the first glance, that the groove found at the anterior thick end 
of the body of the Vertumni, and regarded as the animal’s mouth, 
cannot be an acetabulum, as it is neither covered by an epidermis nor 
an epithelium ; and as no where, in this groove, is the peculiar structure 
of an acetabulum to be distinguished. The wide canal, which stretches 
from the groove longitudinally, in the body of the Vertumnus, is con- 
nected with an innumerable multitude of larger and smaller sinuses, 
which lie buried in the other parts of the animal. The whole paren- 
chyma consists of irregular cells, with wide meshes, which can be blown 
up through the opening in the groove of the Vertumnus, like the paren- 
chyma of the lungs of an Amphihium. 
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