148 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
not raised into wart-like protuberances or papillae, as described in 
some species of Cucumaria, but is smooth. The suspensors, which 
are a continuation of the external connective-tissue layer of the 
alimentary tube, are arranged in ten longitudinal rows upon the 
surface of the pharynx, from which they pass through the peripha- 
ryngeal cavity to the wall of the calcareous ring. They contain 
muscle fibers which serve as dilatators of the pharynx. 
The stomach is a short, straight tube 1.5 cm. in length, of a uni- 
form diameter of about 3 mm., and of a whitish color. It. extends 
from the ring canal to a point just behind the region where the 
reproductive tubules unite. A constriction separates it from the 
small intestine. The outer surface is smooth; the inner surfac is 
raised into irregular, rounded prominences. Its walls are slightly 
thicker than those of the succeeding portions of the alimentary tube. 
In Cucumaria frondosa, as | have made out, the walls are very 
thick compared with those of the small intestine, and by this fact, 
as well as by the small and uniform caliber of the stomach, the 
two parts are well marked off from each other. Quatrefages (’42) 
and Kingsley (81) are the only writers on holothurians who, so 
far as I know, have failed to note this differentiation into stomach 
and intestine. The distinction might readily be overlooked in 
Caudina, but it is very obvious in Cucumaria. 
In a fresh specimen the small intestine (Plate 4, fig. 46) is 
easily distinguished from the stomach and the large intestine by 
its reddish color, which is due to the very abundant blood supply. 
It extends backward about one third of the length of the animal, 
turns to the left side of the body, and runs forward as far as the 
posterior end of the stomach, where it joins the large intestine. 
The small intestine of Caudina resembles that of other holo- 
thurians in the thinness of its walls and in the presence of 
irregular transverse folds, which occur upon the outer surface. 
The inner surface is likewise thrown up into numerous transverse 
folds, which are smaller and more abundant than those upon the 
external surface. 
The large intestine differs from the small intestine mainly in its 
paler color and larger caliber. It turns sharply near its beginning, 
and runs backward on the ventral side of the other viscera to the 
cloaca, which begins nearly opposite the bend in the small intestine. 
