No. 415.] NORTH-AMERICAN INVERTEBRATES. 583 
manubrium of medium size, with four prominent and branched oral tentacles ; 
gonads form prominent masses on body of manubrium. Hydroid (?). 
Bougainvillia (Margelis) carolinensis Ag. (¥ 1G. 46). 
Bell subspherical, wall becoming very thick over the aboral part; radial 
canals four, inconspicuous; marginal tentacles in four clusters, of about ten 
each; in young specimens just liberated there are but two in each group 
and the bell is less globular, while the oral 
tentacles are simple; later these become 
dichotomously branched about three times ; 
ocelli are grouped about the base of each of 
the four triangular sensory bulbs. One of 
the commonest of our Medusz, reaching 
at maturity a size of about eight mm. Color 
greenish or greenish-blue. Hydroid, — 7274. 
Bougainvillia superciliaris Ag. 
In general form and aspect very much like 
the preceding species, but of larger size and 
different shape, being somewhat obovate 
the marginal tentacles are also more numerous as well as longer, a character 
common also to the oral tentacles, while the manubrium is broader and 
shorter. Ocelli as in the former. Of yellowish color. Hydroid, — /é7d. 
Fic. 46. — re 
carolinensis Ag. 
Bougainvillia gibbsii Mayer. 
Very similar to the preceding, distinguished according to Mayer by the 
relatively greater height and smaller width, and by the short and broad 
manubrium, which in cross-section is cruci- 
form. (Cf. Bull. Mus. Comp. Zoöl, Vol. 
XXXVII, No. 1,-p. 5.) Hydroid (?). 
Nemopsis bachei Ag. (FG. 47). 
In general characters Nemopsis has many 
features in common with Bougainvillia, such 
Fic. 47. — Nemofsis bachei Ag. in the number and character of the marginal 
tentacles, more particularly in the pair of erect, 
clavate ones which spring laterally from the tentacular bulbs, as shown in 
the figure. Again, the gonads present characteristic differences, arising 
from the basal portion of the manubrium and extending beneath the radial 
