TRACHYMEDUS.E — CUBAIA. 351 



GENERIC CHARACTERS. 



Olindiadae similar to Gonionemus, but with tentacles of two sorts, one set arising from the 

 sides of the exumbrella above the margin and the other set arising from the bell-margin. 

 Lithocysts projecting outward as in Gonionemus. No centripetal canals. 4 radial-canals, 

 4 gonads, 4 lips. 



This genus is closely related to Vallentinia Browne, 1902, but in Vallentinia the lithocysts 

 are inclosed and on the inner side of the margin, whereas in Cubaia they are external and on 

 the lower side of the margin between the tentacles. 



Cubaia differs from Olindias in that there are no centripetal canals. 



These medusae are found in shallow water over coral flats in the Bahamas and off the 

 Florida Reefs. In habits they closely resemble Gonionemus. 



Cubaia aphrodite Mayer. 

 Plate 46, fig. 6; plate 47, figs. 1 to 7. 



Cubaia aphrodite, Mayer, 1894, Bull. Museum Comp. Zool. at Harvard College, vol. 25, p. 237, plate 2 figs. 1-3; 1904, Mem. 



Nat. Sci. Brooklyn Inst. Museum of Arts and Sci., vol. i, No. 1, p. 21, plate 5, figs. 43-49- 

 Gonionemoidti geophila, Mayer, 1900, Bull. Mus. Comp. Zool. at Harvard College, vol. 37, p. 62, plates 3-5, figs. 6-1 1. 

 Ireniopsis primordialis (young medusa;, green variety), Mayer, 1894, Bull. Mus. Comp. Zool. at Harvard College, vol. 25, p. 



238, plate I, figs. 3-6. 



Mature medusa (plate 47, fig. 3). — Bell slightly flatter than a hemisphere and about 12 mm. 

 in diameter. About 80 tentacles, of which about 20 project from the sides of the bell in a zone 

 above the bell-margin (plate 47, fig. 7), their entodermal cores extending through the gelat- 

 inous substance of the bell to the ring-canal. These tentacles are ringed at regular intervals 

 with about 8 nodular swellings containing nematocysts. On the aboral side, near outer end 

 of each tentacle, there is a large adhesive disk, while beyond this the short, tapering extremity 

 of the tentacle bends at a right angle to the main shaft. This extreme tip of the tentacle bears 

 a large grape-like cluster of nematocyst-cells. 



The remaining 50 to 60 tentacles arise from the bell-margin (plate 47, fig. 6), at a lower 

 level than the zone of origin of the adhesive tentacles. They are somewhat flexible and project 

 downward rather than outward. They have no adhesive disks, but are provided with 25 to 30 

 rings of nematocysts and terminate each in a knob-like cluster of nettling cells. 



There are about 35 closed, vesicular lithocysts, each containing a single spherical con- 

 cretion and all arising from the bell-margin close to the bases of the marginal (non-adhesive) 

 tentacles; they project downward freely into the water. The cyclical order of appearance of 

 tentacles and lithocysts is identical with that in Gonionemus described on pages 345 and 346. 

 Velum well-developed. The circular vessel is simple and narrow and without centripetal 

 diverticula. There are 4 straight, narrow radial-canals, upon the mid-regions of which are 

 the papilliform, reflected gonads. Manubrium flask-shaped; 4 simple, cruciform lips. 



The entoderm of the manubrium, gonads, and circular canal is dull rosin-yellow. There 

 are 4 green, entodermal pigment-spots on the manubrium near the points of origin of the 4 

 radial-canals. The internal entoderm of the bases of the adhesive tentacles is rich magenta- 

 purple, while an intense green color extends a short distance outward into the entodermal 

 shaft of the tentacle. The bases of the non-adhesive tentacles are dull-green without the ma- 

 genta color. In some specimens the magenta color is absent. The gonads sometimes display 

 scattered, dark-colored pigment -granules. This medusa is very active, swimming rapidly 

 with a few powerful pulsations and then slowly sinking down with tentacles outspread. It 

 often attaches itself to objects by means of its adhesive disks. 



Development of the medusa. — When 1 mm. in diameter (plate 47, fig. 1) the bell is 

 higher than a hemisphere and the exumbrella surface regularly sprinkled with nemato- 

 cysts. There are 16 tentacles. The radial and interradial tentacles have as vet no adhesive 

 disks but terminate in simple nematocyst-knobs. The 8 intermediate tentacles, however, 

 have such disks. There are only 4 lithocysts at this stage and the manubrium is rudimentary. 



When 6 mm. in diameter (plate 47, fig. 2) the bell is hemispherical. There are about 

 20 sucker-bearing tentacles alternating with an equal number of nematocyst-bearing ones, 



