1873.] 339 [Morse. 
trace of an anus has been detected in Thecidium, Waldheimia, Rhynch- 
onella, and several other genera that have been examined. In the 
very early stages of Terebratulina, [have seen the rejectamenta es- 
cape from the mouth, and in no case has the appearance of an anal 
perforation been discovered. In Terebratulina, the alimentary tract 
pursues a direct antero-posterior course without convolutions, while in 
_Lingula and Discina the anus terminates anteriorly on the right side. 
In Lingula, the intestine makes a few turns, while in Discina it makes 
a single turn to the right. 
In many worms, diverticular channels often spring from the lateral 
walls of the intestine. In certain worms the liver appears as pro- 
trusions of the alimentary canal. 
In Brachiopods the liver is composed of masses of ccecal ramifica- 
tions which in young Terebratulina, Rhynchonella and Discina, com- 
mence as simple diverticular channels of the stomach. 
In Lingula pyramidata, an examination of these ceca to their 
extremities revealed the presence of diatoms and other food, showing 
that the contents of the stomach enters these diverticular processes, 
and that the process of digestion is carried on in these parts, as in 
the lower worms. The fact that in young Rhynchonella, a distinct 
peristaltic action is seen going on in the hepatic ceca strengthens 
this supposition. While the brown hepatic lines are arranged par- 
allel to the longer axis in the ceca in Terebratulina, in Rhynchonella 
they are curiously arranged in a spiral manner. 
In the higher worms, the intestine is freely suspended in the peri- 
visceral cavity, and held there by delicate membranes which spring 
from the parietes of the body. (See Fig. 1.) 
In Brachiopods, the intestine is likewise suspended freely in the 
perivisceral cavity by delicate membranes which. spring from the 
parietes of the body. These membranes were called by Huxley, the 
gastro-parietal, ileo-parietal, and lateral parietal bands. (See Fig. 7.) 
Cephalic Region. 
In many of the tubicolous Chetopods, as well as in Phoronis, the 
head is furnished with a tuft of ciliated cirri. Sometimes these 
appear to surround the mouth in a single circle, as in the marine 
Polyzoa, and in certain fluviatile forms. In others, they spring from 
arms, spreading like two fans in some, while in others, each arm 
is developed into a closely wound spiral of several turns. These 
spring from what has been called a cartilaginous base. In Profula 
media Stimpson, each arm makes a single graceful turn. The cirri 
