MUSEUM OF COMPARATIVE ZOOLOGY. 151 
tentacular knobs, which resemble stalked capsules, in each one of which is con- 
tained a number of lasso-cells (?). The knobs near the end of the tentacle are 
more scattered. The surface of the tentacle is rough. Four meridional lines 
or areas extend from the tentacular bulbs along the surface of the bell to its 
apex. To these structures, which are filled with bright cells, the species owes 
its name, I am in doubt whether they are continued the whole distance to 
the apex. Near the bulbs of the tentacle they form four areas, broader than 
the meridional lines, and otherwise differentiated from them. 
The otocysts are wanting. 
Locality, Newport, in September. 
The genus Gemmaria, if this form with four tentacles is the adult, is closely 
allied to Zanclea of Gegenbaur. 
Dinematella cavosa, n. g. & s. 
Plate II. Figs. 2, 3, and Plate IV. Fig. 3. 
Many specimens of a jelly-fish closely allied to Stomatoca apicata were taken 
in the summer of 1880. This medusa has generally been confounded with 
S. apicata, being looked upon as a variety, or as its male. 
The most striking superficial difference between the two genera is in the 
color of the ovaries, and their peculiar shape. Mr. Agassiz mentions in 
“North American Acalephæ ? examples of S. apicata where the sexual organs 
are cream-colored. He may have had the same medusa whichis here described, 
and which is considered a wholly different genus from Stomatoca. The most 
important anatomical peculiarity of this new genus is the presence, in the api- 
cai prolongation of the bell, of a cavity, which almost fills the whole of this 
part. The bell has a conical apical projection which is not as high as a like 
protuberance in Stomatoca. The height of the projection is not more than one 
half that of the bell itself. In young specimens it is very small. The cavity 
within occupies all the lower part of the projection, and has aform which would 
contain the frustum of a cone, The contents of the cavity is a liquid identical 
with that which circulates in the marginal and radial tubes. A similar cavity in 
the apical prolongation of the bell in Ctenaria is said by Haeckel to contain pla- 
nule. It is hardly possible in alcoholic specimens to distinguish the planulæ of 
Dinematella from particles of chymiferous fluid. The cavity in the apical pro- 
jection of this genus is not a brood sac, and has not been observed with young 
meduse within, The extremity of the prolongation on the apex of the bell is 
solid, forming a gelatinous hemisphere without external opening, which caps 
the top of the cavity. In a younger specimen, the walls of this cap were pene- 
trated by a tube, through which, when attached to the hydroid, their cavities 
probably communicated. Dinematella probably buds from a hydroid, and this 
cavity never serves as a brood sac, at least for stages more developed than the 
planula. In older specimens there is no communication between the cavity 
and the surrounding medium, as in Cfenaria. The color of the bell is light 
green. 
