on the Natural Group of Tunicata. 543 
colour I cannot ascertain; but if it be the same as that of the - 
specimen in spirits, it is cinereous, rather yellowish. The exter- 
nal orifices have scabrous rims, are very minute and scarcely at 
all prominent. The branchial orifice is quadrifid, and placed 
exactly half-way down the side. The anal orifice is on the same 
line with it and the pedicle, but is placed opposite to this last, so 
as to be terminal, having its external surface apparently without 
rays ; in both respects being totally different from the anal orifice 
of Boltenia. 
. The entrance of the branchial cavity is provided with a cir- 
cular range of ten or twelve unequal tentacula, which are com- 
posite or divided into laciniz at the extremity, which laciniz are 
again so minutely divided as to be almost plumate. The bran- 
chial pouch has about fourteen folds, and its net-work is very 
indistinct and lax, the transverse nervures being perhaps the 
most visible, particularly towards the branchial orifice. "The 
folds of the branchiæ are most easily seen on the inside of the 
branchial pouch. 
The pharynx is situated rather higher than the branchial ori- 
fice; and the esophagus, which is about half the length of the 
stomach, after ascending to the highest part of the branchial 
vein, descends, and gives rise to a simple but enormous stomach, 
having a longitudinal division, marked somewhat deeply, and 
which runs almost the whole length of the body in a line between 
the base of the pedicle and the anal orifice. The intestine is 
exceedingly short, and apparently descending in a line with the 
stomach ; the rectum is cylindrical, and anus simple. Such, at 
least, is the description of the digestive apparatus of this animal, 
if we give the name of pharynz to that end of the intestinal canal 
which opens into the branchial cavity, and the name of anus to 
that end of it which is free ; and there is no doubt that such a de- 
scription makes it an animal totally different from Boltenia, and in 
fact 
