486 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
test both without and within was generally decidedly more brown 
than gray or greenish. Many of the specimens have on one side an 
area where the test processes are few and short and the adhering mate- 
rial scanty, looking as if the body had been attached by that area or 
at least pressed against some other object. In a few specimens the 
siphons arise a considerable distance apart. The largest specimen 
examined measured 24 mm. in length, 16 mm. in dorso-ventral diame- 
ter, and still less in transverse diameter, but the usual dimensions 
are not more than two thirds as great as in this specimen. 
Mantle musculature slight, muscle bands conspicuous chiefly near 
the siphons, from whose bases stout closely placed radiating bands 
extend for some distance, then taper abruptly' and either end or become 
very narrow and inconspicuous. These radiating bands are overlaid 
by a layer of circularly placed fibers. Short thick oblique muscle 
bands occur also in considerable numbers near the mid-ventral line 
on each side of the body, but do not extend across the region of the 
endostyle. 
Tentacles of at least four orders fairly regularly arranged. Large 
tentacles few, irregularly bipinnately (to some extent tripinnately) 
branched. The branchlets, which have the tip rounded but not 
perceptibly enlarged, are borne on the main stem (between the 
origins of the larger branches) as well as upon the large branches. 
The smallest tentacles are nearly or quite simple. 
In the specimens examined the orifice of the dorsal tubercle was 
simply C-shaped or horseshoe-shaped with the open interval directed 
obliquely (sometimes forward, oftener backward) to the left. 
Dorsal lamina very broad and stout, with a smooth, somewhat 
rolled margin. 
Branchial folds well developed, seven on eacli side. Internal longi- 
tudinal vessels numerous and fairly stout; they are well developed 
both on the dorsal and on the ventral of the two leaves forming each 
fold and generally occur only on the folds, though sometimes one may 
lie in an interspace but close along the base of a fold. In a very 
large individual these vessels numbered as follows: 
mdv. (10) (12) (12) (11) (9) (7) (6) en. 
but this is a somewhat greater number than occur in most specimens, 
and in the normal more or less dorsally directed position of the folds 
some of the vessels are of course concealed from view. 
