244 E. A. ANDREWS 
into the blood space as the tubular glands alluded to above. The 
orifice at the tip is small and is not closed by any muscle, but 
apparently by blood pressure only. The part of the tube lined 
by cuticle has its lumen much reduced by a valve, or great longi- 
tudinal ridge, which extends out as far as the abrupt bend at the 
orifice. Ina cross section (fig. 3) this ridge is well seen, as is also 
the fact that some muscle fibres run into it and that the glands are 
chiefly on the side opposite the ridge. The ridge appears to act 
like a valve to hold this part of the tube closed, while contractions 
of the muscle would tend to open the tube wide and let the sperm 
pass to the orifice, which would then be forced open by the internal 
pressure of the sperm squeezed by the muscles of the wall all along 
the length of the duct, or some extent of it at all events. 
The upper part of the duct, as seen in the cross section fig. 4, 
has its thick muscles arranged chiefly in transverse fibres and is 
lined by an epithelium that evidently in large measure breaks 
down to furnish a great mass of secretion about the sperms. It 
is probably this secretion that envelops the sperm in the form of 
macaroni-like tubes, when they pass out in a slow stream. 
THE STYLETS 
The most complex of the organs concerned in sperm transfer 
are the modified limbs of the abdomen which we will call the sty- 
lets. In the male the sixth pair of abdominal appendages form 
the large side parts of the tail fan while the third to the fifth in- 
clusive are the simple and apparently rather useless swimmerets. 
The first and second pairs are specially constructed to serve as 
transfer organs for the sperm. 
These appendages of the first and second somites are much 
stouter and longer than the following swimmerets and have a very 
firm attachment to the abdominal sterna. The calcified ridge 
across the middle of the sterna is much more developed in the 
first and second somites, and where the appendages are fastened 
it rises up as a decided elevation which remains as a stump when 
the appendage is cut off. On the second somite these stumps are 
far apart, (some 10 mm. in a male of 100 mm.) while on the first 
