446 THE AMERICAN NATURALIST. [Vor. XXXVI. 
walls of the cesophagus. Its movements are doubtless to a great 
extent dependent on the contractions of the cesophagus, which, 
as described below, is converted into a sort of muscular pharynx. 
The stylet can hardly be moved much beyond the external 
opening of the rhynchodzeum, and from a study of its structure 
alone it is hard to conceive how it can be moved for even this 
short distance, imbedded as it is among the other tissues. By 
crushing and many kinds of stimuli I have seldom been able to 
cause the worms to move the stylet region to any extent either 
forward or backward. It nearly always remained in the vicin- 
ity of the brain, as shown in the figures. It is my opinion 
that the proboscis can be everted only far enough to bring the 
stylet a little beyond the opening of the rhynchodzeum on the 
tip of the snout, as figured by van Beneden (61), and that 
the cesophageal muscles aid in this movement. At the tip of 
the snout the stylet can puncture the tissues and blood vessels 
of the crab’s gills. With the rhynchodaeum of the worm widely 
opened and closely applied to the point of puncture, the blood 
and nutritive fluids exuding from the wound can be drawn 
directly into the rhynchodzeum and thence into the cesophagus 
by the contraction of the muscular walls of the latter. 
The cesophagus, which leaves the rhynchodzum just in front 
of the brain (Fig. 6), passes beneath the ventral commissure as 
a narrow tube lined with rather flat cells, as in other genera. 
Just back of the brain, however, it becomes enormously enlarged 
with high, columnar, ciliated epithelium, richly provided with 
gland cells. This portion of the cesophagus is highly muscular 
and somewhat barrel shaped (F ig. 6), projecting a little way 
backward into the broad intestine which immediately follows 
posteriorly. Its posterior portion is therefore surrounded by 
the intestine, as shown in Figs. 6, 7. Its opening into the 
intestine is wide and has thickened lips. The backward and 
forward motion of this barrel-shaped portion of the cesophagus 
in all probability aids in the eversion of the proboscis, as well 
as acts as a suction pump to draw in the nutritive fluids from 
the crab's gills. 
The intestinal lobes surrounding the end of the cesophagus 
(Figs. 6, 7) indicate rudiments of the intestinal caeca found in 
