THE PELAGIC FAUNA AND FLOKA. 203 



siphonophores, taken from the sounding-line by Dr. Studer on 

 the " Gazelle," may have come, as I have so often observed in 

 the Caribbean, from any depth. I do not mean, of course, to 

 deny that there are deep-sea medusae. The habit common to 

 so many of our acalephs (Tima, ^quorea, Ptychogena, etc.) of 

 swimming- near the bottom is well known ; Dactylometra moves 

 near the bottom, and Polyclonia remains during the day turned 

 up with the disc downwards on the mud bottom. I only wish 

 to call attention to the uncertain methods adopted for deter- 

 mining at what depth they actually Hve. 



One must have sailed through miles of Salpse, with the asso- 

 ciated crustacean, annelid, and mollusk larvae, the acalephs, 

 especially the oceanic siphonophores, the pteropods and heter- 

 opods, with the radiolarians, globigerinse, and algae, to form an 

 idea of how rich a field still remains to be explored. The 

 pelagic fauna in the course of the Gulf Stream is probably not 

 surpassed in variety by that of any other part of the ocean. 



When they die and decompose, the pelagic forms, both ani- 

 mal and vegetable, 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 examining the intestines of the 

 deep-water echinoderms. We can thus account for the pre- 

 sence at great depths of much of the necessary plant-food 

 needed for the herbivorous types living in the continental and 

 abyssal regions. The variety and abundance of the pelagic 

 fauna and flora, and their importance as food for marine ani- 

 mals, are as yet hardly reahzed. 



According to the recent investigations of Regnard and Certes, 

 decay and decomposition do not progress rapidly in deep water, 

 the great pressure and the absence of light and heat being un- 

 favorable to such progress. This mass of slowly decomposing 

 material, which accumulates on the bottom of the ocean, mixing 

 with the ooze, forms the organic slime which all dredgers have 

 brought up, and which in early days of deep-sea investigations 

 was regarded as a special organism of the highest scientific 

 interest. 



There seemed something providential, indeed, in the existence 

 of this primordial pap, laid out in the thinnest layers over the 



