COE: TERRESTRIAL NEMERTEAN OF BERMUDA. 547 
the only ovum to arrive at maturity, except in the comparatively 
few cases in which the gonad matures two ova. 
Previous to the maturity of the ova, a distinct duct is formed 
which leads from the ovary to the exterior of the body. This duct 
usually opens above the lateral nerves, and through it spermatozoa 
from another individual gain access to the contained ovum. The 
duct then closes up and the developing embryo is isolated from the 
outer world. 
If two ova be present, it sometimes happens that only one is 
sufficiently mature to be fertilized, so that such gonads later contain 
in addition to the single embryo an ovum which is unable to develop 
because the closing of the duct leading from the exterior of the body 
to the ovary has prevented the entrance of other spermatozoa at 
the proper season. Such 
an ovum eventually de¬ 
generates, and its sub¬ 
stance is absorbed bv the 
other tissues, although it 
may remain until the em¬ 
bryo developing from its 
sister cell has become near¬ 
ly mature. 
The details of the de¬ 
velopmental processescon- 
cerned in the formation of 
the mature ovum agree in 
most respects with the ac¬ 
counts given by Mont¬ 
gomery ('95) and Bohmig 
(’98) for Stichostemma. 
The youngest gonads 
occur as small clusters of 
oval cells situated in a 
longitudinal row in the 
body parenchyma imme¬ 
diately above the lateral nerve on each side of the body. As a rule 
about two gonads are situated between each pair of intestinal lobes 
(fig. B), although by their further growth and enlargement adjacent 
gonads grow past each other so that when mature a transverse 
Fig. B.— Portion of longitudinal section of body of 
a worm with nearly mature ova, showing the 
relations of the genital pouches, each of which 
contains a single ovum ( ov .) surrounded by a 
thin follicular epithelium (fol .), and the less 
numerous intestinal caeca ( cae. in .); mu.vg.prb ., 
muscular layers of proboscis sheath; tis.co'nt., 
connective tissue of body parenchyma, x 55. 
