LEUCKART, ON PENTASTOMUM TANIOIDES. 193 
The observations contained in the foregoing paper, and the 
conclusions summed up im the five propositions just stated, 
immediately apply, it should be observed, only to the Pen- 
tastomum tenioides of the dog; although in all essential points 
they might be equally applied to the other species of Pen- 
tastomum as well. This the author believes he will be able 
to show in a further series of experiments. 
In the course of the last year he had an opportunity, besides 
P. tenioides, of examining a large number of other Penta- 
stomata, some in a condition of ‘sexual maturity and some 
in an immature state. Of the former, he notices P. pro- 
boscideum from the lungs of Lachesis and Boa constrictor ; 
P. multicinctum, Harl., from the lungs of the Cobra di Ma- 
rocco; and P. oxycephalum from the lungs of the Cayman. 
All these forms agree with each other and with Pent. 
tenioides in the circumstance that they are without the crown 
of spines and accessory hooks; and further, that they live 
free in the interior of certain organs filled with air. 
The sexually undeveloped Pentastomata examined by him, 
on the other hand, presented, without exception, accessory 
hooks and a crown of spines, although they exhibited con- 
siderable diversities in size and form, more especially in the 
latter. These forms, therefore, associate themselves with P. 
denticulatum. This analogy is the more important, since 
one of these undeveloped forms in all probability belongs to 
the P. oxycephalum noticed above, which, in the fully deve- 
loped condition, possesses none of the organs in question. 
From these observations, it seems to the author not too 
bold to conclude that the second species of Pentastomum 
(P. constrictum, V. Sieb.), found by Pruner and Bilharz, in 
Egypt, in man, may also represent an immature young form. 
He is inclined to adopt this opinion, not only because the 
form in question occurs encysted in the liver, but more espe- 
cially because Bilharz (‘ Zeitsch. f. wissen. Zoolog.,’ Bd. iv, 
p- 68) says respecting it, that the hooks corresponded with 
those of P. denticulatum, and consequently were furnished 
with accessory hooklets. It is true that V. Siebold (op. cit., 
vil, p. 831) expressly states a particular, hardly reconcileable 
with this view, viz., the absence of the circlet of spines; but 
this perhaps merely proves that the apparatus is exceedingly 
minute, and discoverable only by microscopic examination. 
The presence also of the sexual organs in the encysted Pen- 
tastomata, which has been adduced by some (Van Beneden) 
as a proof of their independence and perfect development, 
ean now of itself be regarded as proving nothing, since the 
author’s researches have established the fact that these organs, 
with all their essential parts, are present during the pupa state. | 
