MAYER: MEDUSA FROM THE TOETUGAS. FLORIDA. 63 



velum is well developed. There are 4 straight radial tubes. The gonads 

 occupy the distal halves of the radial tubes, but do not quite extend to the 

 circular vessel. They present the appearance of a series of papilHform, or fin- 

 ger-shaped, processes that are crowded alternately to one side and the other of 

 the radial tube, very much as is the case in Gonionemus vertens. The probos- 

 cis is a simple tube with 4 prominent lips. There are 4 radially situated 

 green-colored spots upon the proboscis close to its junction with the 4 radial 

 canals. 



Young Medusa. — Figures 10, 11, Plate 5. The youngest medusa observed 

 was 1.7 mm. in diameter. The bell was high and quite thick, and its aboral 

 surface was covered with nematocyst capsules. The 16 sucker-bearing tenta- 

 cles were already present, although the suctorial disk was visible upon only 8 

 of them. Figure 11 is a side view of the end of one of these young tentacles 

 showing the beginning of the formation of the suctorial disk. There were 7 

 otocysts present. The velum was very prominent. There were no traces of 

 genital organs present. The proboscis possessed a distinct peduncle. The 

 color of the genital organs, bell margin, and proboscis of this medusa is pearly 

 white. The entoderm of the tentacle bulbs and of the radial tubes in the 

 region of the gonads is green. The ocelli ? of the proboscis are green. 



The adult medusa would frequently lie flat upon the bottom of the aquarium 

 ■wath its oral surface upward (Figure 9, Plate 4). In this position the sucker- 

 bearing tentacles would be stretched far out and the suckers would anchor the 

 medusa to the bottom. The nematocystic tentacles, on the other hand, would 

 wave freely upward apparently in position for the capture of prey. When 

 disturbed the medusa would swim actively about for a few moments, and then 

 reassume its characteristic position of rest. 



This medusa was common at Key West from May 27-June 10, 1897. 



HALICALYX, Fewkes, 1882. 

 Halicalyx tenuis, Fewkes. 



Figs. 13, 13, Plates 5, 6. 



Halicalyx tenuis, Fewkes, J. W., 1882, Bull. Mus. Comp. Zool. Harvard Coll., Vol. 

 IX. p. 277, PI. VII. Fig. 15. 



^ Generic Characters. _ This genus is closely allied to Gonionemoides, but 

 differs from it in that none of the tentacles bear suctorial disks. The tentacles 

 are of two distinct kinds and arise at different levels from the bell margin. 

 The circular vessel gives off blind centripetal branches. There are otocysts at 

 the bases of the tentacles. Tentacles numerous. 



Specijic Characters. — The bell is 25 mm. in diameter and is hemispherical. 

 It is quite thick at the aboral pole, but becomes constantly thinner as one 

 approaches the margin. The gelatinous substance is of very rigid consistency. 



