LEUCKART, ON PENTASTOMUM TENIOIDES. 183 
arrived at sexual maturity. Their ovaries only just showed 
the commencement of the formation of ova, and the vagina 
(which at the same time serves as a uterus, and fills the 
entire cavity of the body with its innumerable convolutions 
in the fully developed female) was as yet not only empty, but 
quite straight and of inconsiderable length (about 12 mm.) 
The question has several times arisen as to the mode in 
which the two spermatic pouches attached to the upper end 
of the vagina can, in the fully formed Pentastomum, be filled 
from without. In order to get over the difficulties of the 
case, and to reconcile the fact with the enormous length and 
impermeability of the vagina when filled with ova, it has 
often been suggested that the statements respecting the sepa- 
ration of the sexes in these parasites may be founded in error. 
The foregoing observation affords the most complete ex- 
planation respecting these conditions. It shows us that the 
vagina of the female is still short and empty at the time of 
copulation, and not longer than the two protrusile tubes 
which represent, according to Van Beneden’s discovery,* the 
truth of which is readily proved, the male copulative appa- 
ratus, and which are variously twisted together and concealed 
in a special muscular sac while in a state of rest. It is, 
indeed, remarkable that the females are not sexually mature 
at the time of copulation, but this peculiarity is not un- 
frequent in the lower animals (which have spermatic recep- 
tacles), especially among insects. 
Of course it cannot at present be my intention to enlarge 
in detail on the structure of the sexual organs of these animals, 
—lI reserve this, as well as the explanation of the organiza- 
tion of the Pentastomata, for a future opportunity,—but I 
may perhaps be here permitted to say thus much, namely, 
that the ovaries are situated on the dorsal, while the sexual 
orifices are on the ventral surface, 7.¢., at the hinder part 
of the body, close before the anal aperture in the females; in 
the male the sexual orifices are placed (and this is the same 
for both the cirrhus-pouches) much further forward, near the 
oral opening. 
The examination of the third dog, which was undertaken 
on the 25th of August, 7.e., about six months after the 
infection with P. denticulatum, gave the same positive 
result as had been derived from the two preceding experi- 
ments. The nasal cavity and the frontal sinuses also har- 
boured a number of P. tenioides, and on this occasion 
individuals of both kinds fully developed. In respect of 
* ‘Recherches sur le developpement des Linguatules.’ Bruxelles, 1849, 
p. 16. 
