MAYER : MEDUSAE FROM THE TORTUGAS, FLORIDA. 59 



single spherical otolith. The velum is well developed. There are 4 straight 

 slender radial canals, which extend down the peduncle to the gastric portion 

 of the proboscis. The peduncle is wide at its base, but not so wide as in 

 Phortis pyramidalis. It extends for a short distance beyond the velar opening 

 of the bell. The gastric portion of the proboscis is cruciform in cross-section 

 and there are 4 simple recurved lips. The 4 gonads are situated upon the 4 

 radial canals a short distance above their junction with the circular vessel. 

 Each gonad is linear, and in the female the ova are quite conspicuous. The 

 gonads and the gastric portion of the proboscis are milky in color, while the 

 tentacle bulbs are cream-colored with greenish entodermal granules. Found 

 at the Tortugas, Florida, in June. 



Phortis pyramidalis. 



Figs. 21, 31a, Plate 10. 

 Eutima pyramidalis, Agassiz, L., 1862, Cent. Nat. Hist. U. S., Vol. IV., p. 363. 



Specific Characters. — Adult medusa. The bell is sUghtly flatter than a 

 hemisphere, and attains a diameter of about 35 mm. There are about 100 

 small slender tentacles, which lack lateral cirri. About 100 otocysts alternate 

 with the equally numerous tentacles. Each otocyst contains a single spherical 

 otolith. (Figure 21*.) There are 4 narrow radial canals. The proboscis is 

 provided with a wide cone-shaped proboscis which fills most of the cavity of 

 the bell, and projects outward for a considerable distance beyond the velar 

 opening. The gastric portion of the proboscis is very small, and is provided 

 with 4 delicately crenulated lips. The gonads are linear and are developed 

 upon the centrifugal portions of the 4 radial canals near to the circular canal. 

 The proboscis, tentacle bulbs, and gonads are of a delicate blue-green color. 

 This medusa is very abundant among the Bahama and Tortugas Islands. At 

 night, when disturbed, it glows with an intense blue-green phosphorescence 

 which is far more brilliant than that of any other medusa that we have 

 observed. 



Young Medusa. — Phortis pyramidalis. In the youngest medusa observed 

 the bell was higher than a hemisphere and 3 nmi. in diameter. There was 

 no peduncle to the proboscis, and the gelatinous substance of the bell was not 

 A'ery thick. There were 4 slender radial tubes and 16 tentacles, only 8 of 

 which had attained to any length, the others being mere basal bulbs. There 

 were about 8 otocysts, each containing a single spherical otolith. When the 

 medusa is about 7 mm. in diameter, the bell is flatter than a hemisphere. The 

 peduncle is well developed and extends beyond the velar opening. The 

 gastric portion of the proboscis has grown very little and is relatively to size 

 of the medusa much smaller than in the younger animal. There are 4 re- 

 curved lips. There are now about -32 tentacles and 16 otocysts. 



VOL. XXXVII. — NO. 2. 5 



