MUSEUM OF COMPARATIVE ZOOLOGY. 211 



relationship is closer between the jelly-fishes of these distant localities than 

 between those of Xarragausett Bay and the Bay of Fundy. The cause 

 of this similarity may readily suggest itself to one who examines the 

 direction of the currents of water which bathe the Kew England coast. 

 The cold currents setting down from the Arctic have brought with them 

 an assemblage of mednsan genera of a facies in marked contrast with 

 that of those brought into Narragansett Bay by warmer waters. This 

 assemblage partakes of the characters of the Arctic, where the current 

 has its birth. While it is true that some of the northern and boreal 

 genera of medusse occasionally round Cape Cod and appear even in num- 

 bers in the bays to the south of this headland, they show by their rarity^ 

 and their dependence upon the prevailing winds at the time, that thew 

 home is to the north.* 



Among familiar examples we "might mention the well-known Cyanea 

 arctica and Aurelia Jlavidula. Hardly a summer passes in which both 

 of these genera are not found in Narragansett Bay near the Newport Lab- 

 oratory, and sometimes the former are in great numbers. I have, how- 

 ever, never seen them at Newport so large or so numerous as those which 

 were taken almost every day at Eastport. Sporadic examples of Turris, 

 Melicertum, and Staurophora are constantly taken in our surface fishing 

 at Newport, but a few* days at Eastport showed me a wealth of indi- 

 viduals of these genera which was unknown to me before. This difier- 

 ence in fauna exists also in the Physophores. Nanomia never ventures 

 into Newport waters, and the magnificent Agalma seems to have its 

 habitat on our coast limited to the southward of Cape Cod. 



If it were the purpose of this paper to contrast the pelagic medusan 

 faunae of the Bay of Fundy and Narragansett Bay, many other instances 

 might be mentioned to show how different the jelly-fishes of the two 



* While there are many boreal medusae which straggle into Narragansett Bay, 

 a still larger number of those whose home is in the tropics make their way into 

 our Southern New England waters through the agency of the Gulf Stream. The 

 surface waters of the Gulf Stream are often blown nearer sliore than is commonly 

 supposed. I have noticed in the water near the Laboratory a rise in tempeiature 

 of over ten degrees in a single flood of the tide. The higher temperature of the 

 water is a good sign that we are to expect oceanic animals in our dip-nets, and we 

 are seldom disappointed. The cause of the elevation in temperature is thought to 

 be directly connected with the prevailing wind from the southeast, where the Gulf 

 Stream lies 



It is believed that the fact that the differences in the temperature of the water 

 — now warmed by the Gulf Stream, now cooled by other currents — is what gives 

 such a great variety to the marine fauna from Ca[)e Cod southward- 



