MAYER: MEDUSA FROM THE TORTUGAS, FLORIDA. 67 



seems probable that they may be absent in some individuals, for we did not 

 observe them in specimens of ^ginella dissonema from the Fiji Islands. In 

 addition to the above-mentioned protuberances there are 4 small iuterradial 

 swellings situated upon the bell margin. There are 8 sensory clubs, 2 in each 

 quadrant (see Figure 32), each one of which contains a single spherical otolith. 

 The velum is large and powerful and is constantly contracting and expanding 

 with great rapidity. There are 4 peronial double canals, each canal being 

 divided into two by means of a longitudinal septum. The proboscis is small 

 and flat, and the mouth is a simple circular opening. There are 8 interradial 

 pouches that extend outward from the stomach into the substance of the bell. 

 The gonads are developed upon these pouches and in the specimen here fig- 

 ured they contained immature ova. The color of the entoderm of the probos- 

 cis and of portions of the entodermal core of the tentacles is intense golden- 

 green. The gonads in the specimens described by Haeckel were rose-red; in 

 ours they were colorless. 



A single specimen was found at the Tortugas, Florida, June 19, 1897. This 

 medusa appears to be very widely distributed. Haeckel found it at the Canary 

 Islands, and we found it in Suva Harbor, Fiji Islands, in January, 1898. 



II. SCYPHOMEDUSiE. 



NAUSITHOB, KOLLIKER, 1853. 



Nausithoe punctata, Kolliker. 



Figs. 67, 68, Plate 33; Figs. 87, 88, Plate 36. 



Nausithoe punctata, Kolliker, A., 1853, Zeit fiir Wissen. Zool., Bd. IV. p. 323. 

 Nausithoe punctata (Marginata albida), Agassiz, L., 1862, Cont. Nat. Hist. U. S., 



Vol. IV. pp. 122, 167. 

 Nausitlioe albida, Carus, V., 1857, Icones Zoutom., Taf. II., Figs. 17, 22, 23. 



Specific Characters. — Adult medusa. The umbrella is quite flat and is 

 about 9 mm. in diameter. There are 8 stiff tentacles, each one of which is 

 about I as long as the bell diameter. The main portion of the entodermal 

 core of each tentacle is solid, but as Vanhoffen, 1892, has shown, the basal bulbs 

 of the tentacles are hollow and connected with the adjacent lappet-pouches. 

 There are 8 marginal sense-organs that alternate with the 8 tentacles. As the 

 Hertwigs (1878, Sinnesorgan der Medusen, Figure 2, Plate 9) and Glaus 

 (1883, Organ. Entwick. Medusen, Figure 47, Plate 7) have shown, each 

 sense-organ consists of an ectodermal eye, provided with a lens and with 

 nerve fibres; and also of an entodermal otocyst containing a number of 

 otoliths. (See Figure 68, Plate 23.) The 16 marginal lappets are long and 

 flexible, and it is by means of their movements that the medusa is enabled 



