on the Natural Group of Tunicata. 533 
The Teruya of Aristotle, or, as Pliny calls them, the Tethee, 
are in general incapable of locomotion; and the three species 
of which I now propose to explain the structure, seem all to 
have been dredged from the bottom of the Northern seas, where 
they lay fixed either to submarine rocks, sand, or sea-weed, or 
to other animals sedentary like themselves. These species all 
belong to the natural family of Ascidide, which corresponds in 
every respect but name with M. Savigny’s Tethyes simples. 
Subgenus. BOLTENIA Sav. 
ExTERNAL CHARACTER. Body with a coriaceous test, sup- 
ported from the summit by a long pedicle, and having 
both orifices lateral and cleft into four rays. 
ANATOMICAL CHARACTER. Branchial pouch divided into lon- 
gitudinal folds, surmounted by a circle of compound 
tentacula, and having the reticulation of its respiratory. 
tissue simple. Abdomen lateral Ovary multiple. 
This generic character differs in some respects from that of 
M. Savigny, and is reformed, for anatomical reasons, which I 
shall hereafter explain at length in my description of the only 
species of the subgenus which I have seen from the late Expedi- 
tion. It is the same species of Linnean Ascidia concerning which 
Captain Sabine says in the Appendix to Captain Parry's First 
Voyage, that it was not unfrequently taken by the trawl on the west 
coast of Davis's Strait, in lat. 70". It is also, as this ardent lover 
shows the affinity of these to Pyrosoma, and of Pyrosoma to Salpa or (as it is some- 
times called, although the name is preuccupied in Botany) Thalia. De Blainville, in- 
deed, goes so far as to call the Lucide ** Salpiens aggregés" ; and although no great 
stress ought to be laid on this author's arrangement, from his obvious wish to obliterate 
the inimitable labours of Savigny, it is clear that the affinity between Pyrosoma and 
Salpa is strong. A fifth group of the Tunicata is wanting to connect the Biphoride 
with the Ascidide ; and I have no doubt that such animals will soon occur to reward 
the industry of those who collect Mollusca and Acrita. 
$72 of 
