82 MACALISTER, ON ASCARIS DACTYLURIS. 
From the head the esophagus passes backwards, and is 
variable in position and length. It is usually curved, with 
its concavity directed forwards, and it forms about one third 
of the entire diameter of the animal’s body; it is not, how- 
ever, uniform in calibre, for in some individuals it exhibits 
slight constrictions, while in others it was dilated into shallow 
pouches. Its cavity seemed to be like that of other ascarides, 
rather triquetrous than cylindrical, and its walls were marked 
with longitudinal strie; but whether these were due to 
muscularity or no I could not positively pronounce, though, 
from the thickness of the coats, it is most probable that it is 
a muscular tube. As remarked by Rudolphi, it is much 
longer and straighter in males than in females, and varies 
from one third to one tenth the length of the entire body, 
being shortest in those females which were crowded with 
eggs, and longest in the adult males, Its lower end, after a 
slight constriction, became suddenly dilated into a globose 
stomach, called by Rudolphi the proventriculus, which is very 
thick in its coats, and filled with a greenish-coloured mass. 
Its cardiac orifice is rather narrow and constricted, while the 
pyloric aperture is wider, and when compressed seems some- 
what valvular, the granular contents passing more freely from 
the stomach to the intestine than in the contrary direction. 
In some individuals this cavity was perfectly globular, in 
others it was slightly conical and flattened; its usual shape 
is that of an oblate spheroid, to the poles of which the cso- 
phagus and intestine are attached. A similar globose cavity 
in Ascaris infecta is described under the name of gizzard by 
Dr. Leidy, in the first part of the ‘Smithsonian Contribu- 
tions, page 43. From the inside of the body-wall three or 
four apparently solid curved processes pass to the wall of the 
stomach, and serve to suspend it in the animal’s body-cavity. 
The intestine commences by a clavate dilatation, which gradu- 
ally narrows, and passes in almost a straight course back to 
the anus, which is a slit-like orifice, situated a little in front 
of the tail. Shortly before it reaches this point the gut ex- 
hibits a slight enlargement, below which the narrower sub- 
cylindrical or pyriform rectum turns off at an obtuse angle, 
and terminates the canal. Around the constriction, which 
marks the origin of the rectum, are arranged four small pyri- 
form sacs, one in front, one on either side, and one posteriorly, 
granular in appearance, and having their narrow peduncles 
or necks continuous with a duct which opens into the gut 
immediately above its termination. In one specimen a spur 
was seen distinctly passing backwards to the body-wall from 
the anterior extremity of the cceca. Concerning the nature 
