No. 2.] A NEW MARINE TRICLAD. 185 
and Bdelloura have nothing to do with forming the egg- 
capsule, but function only as receptacula seminis. On this 
supposition it is difficult to explain the presence of a secretion 
in the uterus unless it serve as a nutrient medium for pro- 
longing the activity of the spermatozoa. It would seem, either 
that the duct of the uterus must function as a vagina, the penis 
being inserted in its orifice during copulation, or that the sper- 
matozoa must be attracted into the uterine cavity. This may 
perhaps be accomplished by positive chemiotactic properties 
resident in the secretion of the uterine epithelium. I take 
this suggestion from Jordan’s interesting paper on the sperma- 
tophores of the newt (91) ; he believes that the spermatozoa 
of this amphibian may be enticed into the recesses of the 
cloacal glands by the glandular secretion. 
9. Breeding Habits. 
B. candida, B. propinqua and S. pellucidum all deposit their 
egg-capsules on the gill-lamellze of their host, Limulus. The 
first species seems to show no preference for a particular 
region of the gill-leaf, but scatters its egg-capsules over the 
whole surface. 2B. propingua selects the basal, or proximal 
region of the leaf, while Syncalidium preters a small area near 
the edge and just lateral to a small marginal callosity which 
forms a brown line with the callosities of the adjacent leaves 
when the gill-book is closed. 
The egg-capsule of Syncelidium (Fig. 5) is about .75 mm. 
long, of an oblong shape and somewhat compressed. It is 
attached by a slender pedicel .5 mm. in length, in such a way 
that one of the flattened sides of the capsule is applied to the 
surface of the gill-leaf. Usually the capsules are arranged 
with their long axes parallel to one another in a little cluster 
near the marginal callosity. The chitinous wall of the capsule 
is thin and transparent, but grows thicker towards the poles. 
Through it the two opaque white eggs or larvae may be distinctly 
seen. I have never found more than two eggs in a capsule. 
Many of the capsules bear at their outer ends one or more 
of the deep blue thece of an infusorium (Fig. 5). These 
