MAYER: MEDUSA FROM THE TORTUGAS, FLORIDA. 55 



cles ; usually one, but occasionally two, being found between each successive 

 pair of tentacles. Each otocyst contains a single spherical otolith. The velum 

 is simple and quite broad. There is a slender circular vessel, and a single 

 straight chymiferous canal extends along the major axis of the bell. In the 

 oldest medusae observed there were 4 manubria. Two equally developed large 

 manubria were situated on either side of the centre of the sub-umbrella, upon 

 the chymiferous canal ; while two small manubria were found upon the same 

 canal centrifugally away from the larger manubria. There was thus no 

 manubrium at the centre of the sub-umbrella. There were two small gonads 

 upon the chymiferous canal immediately centrifugal from the small manu- 

 bria. The entoderm of the manubria and of the basal bulbs of the tentacles is 

 of an opaque glistening white. The supporting lamella of the bell is of a deli- 

 cate green. 



Young Medusa, — In the youngest medusa observed, there were but 2 

 manubria situated upon the chymiferous canal on either side of the centre of 

 the disk. The major axis of the bell was 2.5 mm. and there was no trace of 

 gonads. About a dozen specimens of this medusa were captured at the Tortu- 

 gas, Florida, from June 30-July 2, 1899. 



It seems possible that the bell of the large medusae may divide by transverse 

 fission, for one individual was found in which there was a decided notch in the 

 bell-margin extending inward in the plane passing through the centre of the 

 siib-umbrella perpendicular to the main chymiferous tube. This notch ap- 

 peared, however, upon only one side of the bell and may have been due to an 

 accident. The main chymiferous canal is of course equivalent, morphologi- 

 cally, to two diametrically opposed radial canals. 



EUCHBILOTA, McCradt, 1857. 

 Eucheilota ventricularis, McCrady. 



Fig. 138^ Plate 38. 



Eucheilota ventricularis, McCrady, J., 1857, Gymn. Charleston Harbor, p. 85, Pi. 

 11, Figs. 1, 2 ; PI. 12, Figs. 1-3. 



This medusa is quite rare at the Tortugas, Florida, and not more than a 

 dozen specimens were obtained. They were remarkable in that the entoderm 

 of the tentacle bulbs and proboscis was of a decided green color. Each otocyst 

 contained 2-4 spherical otoliths. In specimens 2 mm. in diameter there were 

 as yet no gonads upon the radial canals. 



