MAYER: MEDUSA FROM THE TORTUGAS, FLORIDA. 69 



DACTYLOMETRA, Agassiz, L., 1862. 



Dactylometra lactea, L. Agassiz. 



Chrysaora lactea, Eschscholtz, F., 1829, Syst. der Acalephen, p. 81, Taf. VII. Fig. 3. 

 Dactylometra lactea, Agassiz, L., 1862, Cont. Nat. Hist. U. S., Vol. IV. pp. 125, 126, 



166. 

 Dactylometra lactea, Agassiz, A., and Mayer, A. G., 1898, Bull. Mus. Comp. Zool. 



at Harvard Coll., Vol. XXXII. p. 7, Pis. XII., XIII., and Fig. 10, PI. VII. 



This medusa is extremely common in Havana Harbor, Cuba, in February, 

 where it swims upon the surfoce during the afternoon hours. It has been de- 

 scribed by Esch-scholtz from the Bay of Rio Janeiro, Brazil. It is occasionally 

 found at the Tortugas, Florida. 



AURBLIA, Peron and Lesueur, 1809. 

 Aurelia habanensis, nov. sp. 



Fig8. 73, 74, Plate 34; Fig. 86, Plate 2G. 



Specific Characters. — Adult medusa. The bell is 240 mm. in diameter. 

 It is disk-shaped, and the gelatinous substance is quite thick. There are 8 

 simple marginal lappets, which bear upon their dorsal surfaces, at a slight dis- 

 tance above the bell margin, a row of numerous short tentacles. There are 

 8 marginal sense-organs that are deeply set within niches situated between the 

 marginal lappets. The radiating chymiferous tubes are very similar to those 

 of Aurelia flavidula, Peron and Lesueur. The mouth-arms, or palps, are long 

 and narrow and extend almost to the bell margin. Their free edges are not 

 lined with a fringe of tentacles as in Aurelia flavidula, but instead are covered 

 with wart-like clusters of nematocy.st cells (see Figures 73, 74, Plate 24). 

 This, indeed, constitutes the principal difference between this species and 

 Aurelia flavidula. The 4 gonads are horseshoe-shaped and there are 4 sub- 

 genital pits. Both the gonads and subgenital pits are smaller than in Aurelia 

 flavidula. The gelatinous substance of the bell is bluish white in color. The 

 genital organs of the males are pink, and of the females white in color. The 

 basal bulbs of the marginal tentacles are often pink. 



This medusa is extremely abundant in Havana Harbor, Cuba, in February. 

 It makes its appearance at the Tortugas in August, but we do not know 

 whether it is found also at Havana at that time or not. 



While in Havana Harbor in February, 1893, we had the opportunity of ob- 

 serving the curious habits of this medusa. During the morning hours not one 

 was to be seen, but at about four o'clock in the afternoon they began to appear 

 in great numbers, and continued to be seen until long after nightfall. 



This species is quite distinct from Aurelia marginalis, L. Agassiz (1862; 



