VAN NAME: COMPOUND ASCIDIANS. 373 
globular, and the intestine has a constriction or valve some distance 
beyond the stomach. The tubules of the gland embracing the intestine 
are clearly visible in some specimens, and are few in number with 
tapering ends. 
The testis is very frequently, if not invariably, divided into two 
glands, which together form a conical mass about which the sperm 
duct is coiled, usually makmg about eight or nine turns. 
Xorth of Cape Cod this form is local and for the most part replaced 
by Tetradidemmim aUndum. There are specimens in the collection 
from a tide-pool on Ten Pound Island, near Gloucester, Mass., and 
others, which if correctly labeled, are from the Isles of Shoals off the 
Xew Hampshire coast. Metcalf (1900, p. oGo) mentions specimens 
of this genus from Casco Bay, Elaine, which he apparently considered 
identical with those found at ^Yood's Hole, and hence with this spe- 
cies, but the writer has seen none from so far north that were of this 
species. 
South of Cape Cod (including also the south shore of the Cape) it 
is the common, and in most places the only, species of the genus. 
Probably all the published records of L. alhidinn and L. lufeolum 
Verrill from that part of the coast refer to it. It is abundant at 
Wood's Hole, EdgartoAvn, and A'ineyard Haven, Mass., on the piles 
of wharves, and in A'ineyard Sound in 4 to 15 fathoms, and often 
grows on ascidians of other kinds, as well as on stones, sponges, 
shells, etc. Other localities are Point Judith, Rhode Island; off 
Stonington, Conn., 4 fathoms, rocky; Noank, Conn.; Peconic Bay; 
Thimble Islands near Stony Creek, Conn., 4 to G fathoms, rocky. 
As compared with the Didemnum [Leptoclinum] found at Bermuda, 
which the writer in his account of the ascidians of that region identified 
after some hesitation with D. [L.] speciosum Herdman, 1886, of the 
Brazilian coast, the test in this species is very much softer and more 
brittle. The Bermuda form generally has larger spicules with more 
rays; in those varieties where they are as small as in D. lutarium, the 
rays are slender and very much more numerous. The present species 
does not, as is the case in the Bermuda species, show a differentiation 
into varieties differing markedly in the size and shape of the spicules, 
etc., but is remarkably constant in its characters. The correspondence 
in the structure of the zooids, however, show^s the Bermuda and the 
New England forms to be very closely allied, so that D. lutarium may 
some time need to be reduced to the rank of a subspecies of D. 
speciosum. 
