580 THE AMERICAN NATURALIST. [VoOL. XXXV. 
Habitat: Found upon the legs and abdominal somites of the common 
crab, Labinia, from which it was repeatedly taken during several seasons. 
Hydroid, — Perigonimus. 
Euphysa virgulata A. Ag. 
Bell elongate oval, or quadrangular in outline; tentacles rather heavy 
and unequally developed, one being much longer and heavier than the 
others ; bases with a pinkish band extending upward 
along the radial canals for a short distance; manu- 
brium cylindrical with simple oral margins and of 
yellowish color; gonads upon the sides of manu- 
brium. In size the medusa is from ten to twelve 
mm. in diameter, of rather active habit and fairly 
common. Nahant, Massachusetts Bay, and south- 
ward. 
Corymorpha pendula Ag. (Fic. 38). 
Bell somewhat unsymmetrical, oblong with sub- 
conical apex; tentacles unequally developed, one 
being quite long and heavy, the others much smaller ; 
manubrium similar to the preceding, both in form 
and color; bases of tentacles 
Fic. 38. — Corymorpha of pinkish color ; size from 
pendula Ag. (After 
Agassiz.) 
five tosixmm. Common along 
the coast, hydroids dredged 
from waters of Vineyard Sound, Massachusetts Bay, 
etc. Hydroid generation, — Corymorpha. 
Hybocodon prolifer Ag. (FIG. 39). 
Bell similar to preceding, but with marked asymme- 
try; a single marginal tentacle of large size, with very 
thick basal portion, from which there bud _ prolifer- 
ously secondary medusz, which in turn similarly bud 
tertiary meduse, several generations in this way being Fic. 39.— Hybocodon 
present upon the parent medusa. In other aspects meee: 
very similar to the preceding. Hydroid generation, — Hybocodon. 
Stomotoca apicata Ag. (FIG. 40). 
Bell rather open and shallow, with an elongate conical projection at the 
apex; radial canals four; marginal tentacles two, which are long and 
slender and highly retractile ; manubrium also retractile, with a four-lobed 
