50 BULLETIN :. MUSEUM OF COMPARATIVE ZOOLOGY. 
The proboscis (p7’b., Figure 28) is long, extending over somites VIII.—xm. 
There is practically no esophagus, as I have used the term, for the pharyngeal 
sac containing the proboscis extends back almost to the beginning of the crop. 
The salivary glands are numerous, often reaching seventy-five or more in 
number in each half of the body. They are scattered usually through somites 
xI.-xvilIl. In Figure 28 they are represented as relatively a little too small. 
The crop (¢glv.) bears seven pairs of large, lateral diverticula directed back- 
ward and often lobed distally. They arise in somites X111.—XIx., always in the 
middle of a somite, as in the other species described. The last pair of crop 
diverticula is, as usual, the largest of all; it may extend back through three or 
four somites, giving off secondary lateral diverticula metamerically, as shown 
in Figure 28. Often, however, when the crop is empty, the last pair of diver- 
ticula is little longer than the preceding pair. 
The stomach (ga., Figure 28) bears, as in other species, four pairs of diverti- 
cula, which arise within the three somites x1x.-xx1. The intestine (in.) extends 
through the six remaining somites, consisting proximally of two distinct cham- 
bers limited by valve-like constrictions and usually situated in somites XXII. 
and xxiu. Distally it is a gradually narrowing tube terminating at the anus 
just behind somite Xxv1. 
e. NePHROPORES, Nervous SYSTEM. 
The nephropores open ventro-laterally, a little anterior to the middle of the 
sensory ring of a somite. The number of nephridia has not been determined 
for this species. 
The brain (cb., Figures 28, 30) lies for the most part in somite vil. The 
arrangement of its ganglionic capsules (Figure 5, Plate 2; Figure 11, Plate 3) 
is usually similar to that found in the brain of G. stagnalis and G. fusca, but 
the capsules are not so closely crowded together, and the supra-cesophageal com- 
missure lies well forward, not being carried back over the middle of the brain 
as in G. stagnalis (Figure 12). The less crowded condition of the capsules in 
this species (Figure 5) explains an abnormality in their arrangement observed 
in the brain of a single individual out of several examined; the two ventral 
capsules of somite 111. (usually found side by side as in G. stagnalis and the 
other species already described) were in this case arranged tandem, just as in 
ganglia in unabbreviated somites. 
Comparing the conditions of the brain capsules in the several species described 
in this paper, one may say that the larger the leech is, the less are its capsules 
crowded. This fact seems to indicate that the capsules, and probably the indi- 
vidual ganglion cells also, do not increase in size proportionally with the growth 
of the leech. This is certainly true of the development of the individual, if not 
also of the race, for in the very young leech the ganglia of the nerve chain oc- 
cur in close succession with scarcely any intervening space, whereas in the adult 
they may be separated by a distance of two rings or even more. 
