MUSEUM OF COMPARATIVE ZOOLOGY. 151 



tentacular knobs, wliich 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 scjittered. The surface of the tentacle is rough. Four meridional lines 

 or arejus extend from the tentacular bulbs along the surface of the bell to its 

 apex. To these structures, Avhich 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 simimer 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 Acalephai " examples of S. apicata where the sexual organs 

 are cream-colored. He may have had the same medusa which is here described, 

 and which is considered a whoUy different genus from Stomatoca. The most 

 important anatomical peculiarity of this new genus is the presence, in the api- 

 cal 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 a form 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- 

 nulae. It is hardly possible in alcoholic specimens to distinguish the planuhc 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 

 medusae within. The extremity of the prolongation on the apex of the bell is 

 solid, fonning a gelatinous hemisphere without external opening, which caps 

 the top of the cavity. In a yoimger 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 ca\nty 

 and the surrounding medium, as in Ctenaria. The color of the bell is light 

 green. 



