MUSEUM OF COMPAKATIVE ZOOLOGY. 153 



between these limits. On drawing up the cylinder and washing out the 

 sieve of the trap, not only did we find that the water contained nothing 

 different from what had been brought up by the cylinder from the 

 lesser depth, but it did not contain even a single Radiolarian. 



On the 15th of July, in Lat. 34° 28' 25'^ N., Lon. 75° 22' 50'' W., 

 we tried the Sigsbee cylinder for a third time, in a depth of 1,632 

 fathoms. With the same precautions before and after using it, the cylin- 

 der was sent to collect first between 5 and^ 50 fathoms (time 30"). The 

 surface was somewhat ruffled, and but little was found on the surface 

 beyond a few Crustacean larvae and Heteropods. The cylinder con- 

 tained Hydroids, fragments of Siphonophores, pelagic Algse, Crustacean 

 larvae, and Heteropod eggs ; forms which differed from these scooped 

 at the surface, but were identical with the species found on previous 

 days at the surface under more favorable surface conditions of the sea. 

 Next, the cylinder was arranged to collect between 50 and 100 fathoms 

 (time of messenger 21" from surface to 50 fathoms, time of cylinder 

 40" to stopper from 50 to 100 fathoms). The water was found to con- 

 tain only a couple of Squillese larvee, similar to those fished up at the 

 surface. The third time the cylinder went down at this station it was 

 lowered to collect from 100 to 150 fathoms (time of messenger from 

 surface to 100 fathoms 45", time of cylinder in passing from 100 

 to 150 fathoms 45"). The water when examined contained nothing. 

 No Radiolarians were found at this station, either at the surface or at 

 any depth to which the cylinder was sent (150 fathoms). 



The above experiments appear to prove conclusively that the surface 

 fauna of the sea is really limited to a comparatively narrow belt in 

 depth, and that there is no intermediate belt, so to speak, of animal 

 life, between those living on the bottom, or close to it, and the surface 

 pelagic fauna. 



The experiments of using the tow-net at great depths (of 500 and 

 1,000 fathoms), as was done by Mr. Murray on the " Challenger," were 

 not conclusive, as I have already pointed out on a former occasion, while 

 the so-called deep-sea Siphonophorae, 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 bot- 

 tom is well known ; Dactylometra moves near the bottom, and Polyclonia 

 remains during the day turned up with the disk downwards on the mud 

 bottom. I only wish to call attention to the uncertain methods adopted 

 for ascertaining at what depth they live. 



