532 F. M. MacFarran, 
Dirona albolineata in this respect is of the greatest interest. Here 
we find a quite short and slender oviduct, extending almost directly 
from the point at which the vas deferens is given off to the atrium, 
opening into the latter at a similar point as in Dirona pieta. "The 
spermatotheca, however, is very large, reaching a diameter of 1,3 mm 
its total length being 4 mm in a large specimen, which is over four 
times the corresponding dimensions in Dirona picta. "The anatomical 
relations of the spermatotheca are exactly the same in the two 
species. 
Equally striking differences in the relative development of 
the same organs are found in the male branch of the hermaphroditie 
duct. In Dirona pieta the vas deferens is very long, often longer 
than the whole animal itself. In it may be distinguished a proxi- 
mal glandular and a distal muscular portion. It is wound in a 
complicated series of coils upon the upper anterior portion of the 
genital complex. Its distal portion at first gives one the impression 
of being an organ of considerable bulk, but celoser examination shows 
that this is largely due to an enclosing sheath of muscle fibres, the 
retractor muscle of the preputium. These arise from the left wall 
of the body, extend across in front of the posterior visceral complex 
and are inserted around the preputial portion of the vas deferens, 
inclosing the closely coiled, distal loops of the duct, and thus ap- 
pearing to constitute a bulky organ. When separated, however, 
the tube is found to be long and slender, the small conical 
glans being borne at the inner end of a preputial tube, 4,0 mm 
from its outer opening. The inner wall of this preputium, which 
becomes the external surface of the intromittent organ when everted, 
is ridged in a somewhat spiral manner, giving the appearance of 
an armature. 
In Dirona albolineata the vas deferens is much shorter. It shows 
also the divisions into a glandular and a muscular portion. The 
preputial region presents the most striking differences. Here it is 
a large, roomy sack, with a strong cone of muscles inserted in its 
proximal portion. At its inner end is borne a very large cylindro- 
conical glans, blunt at the extreme tip and bearing on its surface a 
very large number of conical eminences, apparently arranged in a 
spiral row of very close turns. These structures resemble an arma- 
ture but there is no trace of a corresponding cuticular thickening 
to form spines. The glans fills up the whole length of the pre- 
putial sack, and is often bent upon itself in addition, which con- 
