on the Natural Group of Tunicata. 547 
When the naturalist happens to consider that he ought always 
to obtain his group before he attempts to find its character, he 
is sure to perceive this truth; and it is on this very principle, in- 
deed, that Savigny, with his usual discrimination, has proceeded 
in the above natural arrangement of the genus Ascidia, which I 
have done little more than borrow from him. To this naturalist, 
whose works I cannot too often recommend to the careful atten- 
tion of zoologists as models for imitation and true examples of 
the method in which Natural History ought to be studied, I 
would willingly have dedicated the following subgenus ; but his 
name happens to have been employed in other branches of the 
science. On account of its ramose ovarium, therefore, I shall 
name this 
Subgenus, DENDRODOA. 
Externat Cuaracter. Body subcylindrical, with both ori- 
fices exceedingly minute and situated on the apex. 
AnatomicaL CHARACTER. Branchial pouch marked only with 
eight folds, and having the reticulation continuous. Orifices 
terminal. Tentacula simple. Liver none. Ovary unique, 
branched, situated between the mantle and the branchial 
pouch. 
DENDRODOA GLANDARIA. 
D. glandiformis, tunicà glabra sub-opacá. 
Tas. XX. 
Descr. Body subcylindrical, with a rounded summit. Envelope 
whitish, subpellucid, coriaceous and smooth, having its base 
rough with agglutinated pebbles ; internally it has a pearly 
lustre, and is thickest towards the base. Orifices so little 
prominent as to be scarcely perceptible without a lens: se- 
parate from each other, and opening with four indistinct 
rays. Mantle muscular, but of uniform substance. 
VOL, XIV. 4B Tentacula 
