THE PELAGIC FAUNA AND FLORA. 



183 



England medusae, such as Cunina (Fig. 90), Eutima, Tracliy- 

 nema, Eucheilota, Liriope, Zanelea, and many other species 

 which have been described by McCrady from Charleston, S. C, 

 are also brought north every year along the course of the Gulf 

 Stream, and during the summer are blown to the westward 

 towards the New England coast and the Atlantic coast of the 

 Middle States by the prevailing southwesterly winds. 



The common green turtle of Florida is caught every year in 

 Narragansett Bay, and the leather-back turtle (Sphargis) has 

 been caught as far north as Massachusetts Bay. 



Fig. 91. — Velella mutica. 



Velella (Fig. 91) is found in large numbers in the Straits 

 of Florida, between Cuba and the Florida reefs. Thousands 

 of this animal are brought by favorable winds and tides into 

 Key West harbor, and are carried by the same agencies be- 

 tween the Tortugas channels. They are usually seen in large 

 schools, and, although capable in a smooth sea of independent 

 movement by means of their tentacles, are practically at the 

 mercy of the winds and currents. They are destroyed in im- 

 mense numbers by even moderate waves, which upset them, 

 drive them ashore, or kill them, if kept below the surface for 

 any length of time. They apparently need a good deal of 

 movement, for when kept in confinement they do not thrive, 

 soon die, and are rapidly decomposed. The dead floats are 

 thrown upon the beach behind Fort Jefferson at the Tortugas 



