LEUCKART, ON PENTASTOMUM TANIOIDES. 185 
very marked manner, so that the similarity with a Mite above 
referred to here shows itself still more conspicuously. The 
anterior extremity of the body exhibits a tolerably large, 
gaping oral aperture, whose lower margin especially is indi- 
cated by a crescent-shaped eversion of the external chitinous 
coverings, which are elsewhere generally very soft. Close 
above this opening lies a boring apparatus, which is very 
much stronger in the embryos of P. proboscideum and P. 
multicinctum, and consists of a dagger-like aciculum, placed 
in the middle and directed straight forwards, and two smaller 
sete curved like a hook. The most characteristic feature of 
this preabdomen consists in the presence of two pair of claw- 
feet, which project laterally from the body and occupy nearly 
the whole of the middle third. 
Van Beneden and Schubart describe these feet as con- 
sisting of two joints, and remark that the two claws form a 
prehensile apparatus. I must dispute, however, the correct- 
ness of these statements, and may do so the more decidedly, 
as I have subjected this matter to a careful examination. 
The embryonal pedal tubercle of P. tenioides forms a 
simple, short, and conical process, which throughout its entire 
breadth projects from the substance of the body, and exhi- 
bits no distinct articulation ; it supports two curved claws at 
its extremity, which are placed, not one behind the other, 
but sede by side, and both are curved backwards at their tips. 
The end of the tubercle supporting these claws is truncate, 
and provided at the margin with a strong, hard, chitinous 
ring. I scarcely doubt that the claws are possessed of inde- 
pendent motion. 
In addition to the above-mentioned chitinous ring, we 
may distinguish other solid deposits of rod-shaped bodies in 
the coverings of the pedal tubercles. In certain positions 
these appear under the form of a two-pronged fork, the 
prongs of which, diverging from the place of origin, run 
downwards, and may be traced up to the extremity of the 
tubercles. A nearer examination shows that in such an 
aspect, the anterior surface of the pedal tubercles is always 
that which is brought into view. I especially recommend 
the profile aspect, in order fully to comprehend this forma- 
tion, by the imvestigation of which one arrives at the con- 
viction that only the two diverging prongs of these rods 
belong, properly speaking, to the chitinous covering of the 
foot, while the stem, which is a continuation from them, has 
no other connexion with the chitinous covering, and projects 
freely into the contractile parenchyma of the body. Evi- 
dently this stem forms a lever, by means of which the motion 
