522 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
the genus. The branchial tube is generally a little the longest, and 
both of them are somewhat tapered, with a swollen base." 
(p. 510) " The Molgula produda also occurred on the sandy mud at 
the 29-fathom locality [about 15 miles east of Block Island, Rhode 
Island]." 
(p. 699) "Off Buzzard's Bay, 25 fathoms, sandy. Massachusetts 
Bay, low-water to 6 fathoms, (Stimpson)." 
No specimens of this animal were found in the collection, or at least 
none were recognized as such. (It will be observed that the distin- 
guishing characters are largely those which could hardly be recognized 
except in living or very fresh specimens.) The only specimens found 
labeled Molgula produda were those from the Gulf of Saint Lawrence 
alluded to above, and evidently were nothing more than a case of 
mistaken identification, as they are BostricJiohranchus pilularis. 
There is no reason to suppose that this animal, whatever it may be, 
occurs in that region. The writer does not venture to identify it 
with any of the other species here described. Were it possible to do so, 
the name produda, owing to the early date of its description (1852) 
would probably have priority over the name here employed. 
Family PYURIDAE Hartmeyer, 1908. 
[=CYNTHIIDAE s. HALOCYNTHIIDAE auct. plur.]. 
Body usually attached. Test generally- tough, opaque, and of 
leathery consistency. Both apertures four-lobed in most forms, but 
exceptions are frequent. 
Tentacles almost always branched. 
Branchial sac usually with more than four (most commonly six to 
eight) longitudinal folds. Stigmata never spirally arranged. 
Intestine always on left side; stomach generally not definitely 
marked off from the beginning of the intestine, into which it tapers 
off gradually. 
Reproductive organs on both sides of body. 
Genus Pyura Molina, 1782. 
[= Cynthia s. HALOCYNTmA auct. plur.]. 
Body of variable form, sometimes with a long stalk. 
Test tough, leathery or cartilaginous. 
Tentacles branched. 
Dorsal lamina broken up into a series of tongue-like processes. 
