MAYER: MEDUSA FKOM THE TORTUGAS, FLORIDA. 39 



Specific Characters. — Mature medusa. The bell is pear-shaped with thin 

 walls, and is 4 mm. in height. There are 40-50 marginal tentacles that are 

 capable of much contraction and extension. There is a single brown, ecto- 

 dermal, pigment spot upon the centripetal side of each tentacle near the point 

 of its junction with the tentacle bulb. The velum is well developed. There 

 are 4 straight, narrow, radial canals. The proboscis is wide and fills about 

 half of the cavity of the bell. The upper portion of the proboscis consists of 

 highly vacuolated cells, or chambers, through the midst of which run the 4 

 radial canals. The mouth opening of the proboscis is found at the end of 

 a short, narrow, cylindrical neck, and is surrounded by 4 radially arranged 

 nematocyst-bearing knobs. The gonads are situated within the proboscis. 

 The entoderm of the proboscis is dull yellow, streaked with brownish orange. 

 The ocelli of the tentacle bulbs are orange, or brown in color. 



This medusa is extremely abundant from the coast of Cuba to Newport, 

 Rhode Island. It is not found north of Cape Cod, Massachusetts. It is very 

 common in Charleston Harbor, South Carolina, where it is infested by the 

 young of Cunoctantha octonaria. This medusa is one of the few that ap- 

 pears to develop from the hydroid stock both at the Tortugas and at New- 

 port, Rhode Island. For while medusae indigenous to the Tortugas are often 

 driven into Newport Harbor by southerly winds, very few of these southern 

 visitors establish themselves permanently in the northern waters. 



The hydroid stock of this species was found by Brooks, 1886, at Morehead 

 City, North Carolina. It is a Tubularian belonging to the genus Dendroclava. 

 Brooks gives a number of good figures of it in his paper in the Memoirs of the 

 Boston Society of Natural History, Vol. III., 1886. 



CYTAEIS, EscHSCHOLTz, 1829. 

 Cytaeis gracilis, no v. sp. 



Figs. 133-134, Plate 36. 



Specific Characters. — Mature medusa; Figure 122. The bell is dome- 

 shaped and a little broader than it is high, and the aboral apex terminates in a 

 slight projection. The animal is 3 mm. in diameter. The gelatinous substance 

 of the bell is of only moderate thickness. There are 8 quite stiff curled tenta- 

 cles ; 4 radial and 4 interradial. The radial tentacles are about two thirds as long 

 as the bell height, while the interradial ones-attain only about one half this length. 

 The basal bulbs of all of the tentacles are large and deeply pigmented. The 

 velum is broad. There are 4 straight, narrow, radial canals, and a simple slender 

 circular vessel. The proboscis is mounted upon a short, wide peduncle. The 

 gastric portion of the proboscis is only about one half as long as the height of 

 the bell cavity. The mouth is a simple, round opening, surrounded by 8 un- 

 branched oral tentacles. 4 of these tentacles are radial and 4 interradial in 

 position, and each one terminates in a knob-like end formed of spindle-shaped 



