STRUCTURE AND DEVELOPMENT OF LOXOSOMA. 281 
L. pes the structure of the generative organs is certainly 
more complicated than in most of the other species, in which 
I have invariably found that mature ovaries and testes are 
mutually exclusive. It is easily shown that individuals contain- 
ing developing embryos in their vestibule are not provided with 
testes in the species of Loxosoma and Pedicellina which I 
have examined. In some cases (as in fig. 16) a vesicula seminalis 
containing spermatozoa is found, although the testes seem to 
be completely absent. This fact, perhaps, indicates that the 
male gonads, which must have been originally present, have 
atrophied in order to make room for the development of the 
ovaries. 
L. Tethyse and L. Leptoclini. — The generative organs, 
in individuals of either sex, consist of a pair of glands situated 
at the sides of the body in the region marked ot. in fig. 2 ; 
they lie on the ventral side of the stomach. In the male 
(fig. 13) the testes are large bodies, consisting of a capsule 
enclosing a mass of sperm mother-cells and mature sperma- 
tozoa (with intermediate stages). I have not studied the 
details of the spermatogenesis. From each testis runs towards 
the middle line a short duct (vd.), opening into the posterior 
side of a large oval vesicula seminalis, which in mature males 
always contains numbers of elongated filiform spermatozoa, 
which execute various movements even before their escape to 
the exterior. The aperture of the vesicula into the vestibule 
is very difficult to discover, but has apparently been seen by 
Yogt, although this observer’s statements have been most 
unjustly questioned by Schmidt. It is worthy of note that 
the ganglion can easily be observed in all mature males, and 
that Schmidt’s identification of this structure as the “ testes ” 
is hence undoubtedly erroneous. 
In the female the gonads have the same position as in the 
male, and open by a single pore into the space between the 
epistome and the ganglion (fig. 14). This pore ( p .) leads into 
an unpaired oval cavity, from which proceeds on each side a 
duct to the ovary. The arrangement in Pedicellina is very 
similar, except for the fact that the unpaired portion is pro- 
