154 BULLETIN OF THE MUSEUM OF COMPARATIVE ZOOLOGY. 



As far as the pelagic fauna is concerned, those who have been in the 

 habit of collecting surface animals know full well that the least ripple 

 will send them below the reach of commotion j Miiller and Baur were 

 the first to adopt the use of a tow-net sunk below the surface to col- 

 lect pelagic animals when the water was disturbed. It seems natural 

 to presume, as we have found from our experiments with the Sigsbee 

 cylinder, that this surface fauna only sinks out of reach of the disturb- 

 ances of the top, and does not extend downward to any great depth. 

 TJie dependence of all the pelagic forms upon food which is most abun- 

 dant at the surface, or near it, would naturally keep them where they 

 found it in greatest quantity. 



Of course, with the death and decomposition of the pelagic forms, 

 they sink to the bottom fast enough to form an important part of the 

 food supply of the deep-sea animals, as can easily be ascertained by ex- 

 amining the intestines of the deep-water Echinoderms. The variety 

 and abundance of the pelagic fauna, and its importance as food for ma- 

 rine animals, are as yet hardly realized. 



One must have sailed through miles of Salpse with the associated 

 Crustacean, Annelid, and Mollusk larvae, the Acalephs, especially the 

 oceanic Siphonophores, the Pteropods and Heteropods, with the Radio- 

 larians, Globigerinse, and Algse, to form some idea how rich a field still 

 remains to be explored. The variety of the pelagic fauna in the course 

 of the Gulf Stream is probably not surpassed by that of any other part 

 of the ocean. 



Newport, R. I., August 20, 1880. 



