Mr. J. W. Fewkes on Deep-sea Medasce. 251 



wliat is now most needed in the study of bathyraetrical zones 

 of marine life are improvements in tlie method of collecting at 

 any depth, so that we can tell exactly at what distance below 

 the surface a nomadic animal is captured. Devices have been 

 suggested, one of which, the so-called " gravitating-trap " of 

 Lieut. Sigsbee, has been described in the ' Bulletin ' of the 

 Museum of Comparative Zoology at Cambridge. I am not 

 aware how extensively this apparatus, or others of similar 

 kind, has been used by those who are in charge of deep-sea 

 exploration, or whether it has been sufficiently tried to test 

 its usefulness *. If Medusae were always as abundant at 

 great depths as they sometimes are at the surface, a device 

 might easily be invented for tlie successful capture of at least 

 a few specimens. It seems more probable that Meduste are 

 not common enough to warrant one in supposing them very 

 numerous, and the difficulty in their capture thus becomes 

 greater, rendering it necessary that some modification of the 

 gravitating-trap be invented f. 



In a letter to Mr. C. P. Patterson (Bull. Mus. Comp. 

 Zool. vol. vi. no. 8) Mr. A. Agassiz calls attention to tlie 

 uncertain methods adopted for ascertaining at what depths 

 free-swimming animals live, and from experiments with the 

 " Sigsbee Trap " concludes (p. 153), while he does not deny 

 that there are certain genera of deep-sea Medusaj, that '' 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-fauna." 



This statement from such a high authority in the study of 

 marine zoology would seem to effectually crush any murmur 

 of belief in intermediate zones in the distribution of oceanic 

 forms of life. While I have the highest respect for this view, 

 I cannot help entertaining an opinion that more observations 

 are necessary before we can accept the proposition that there 



* " Results of Explorations made by tlie Steamer ' Albatross ' oft* the 

 Northern Coast of the United States in 1883," Aimiial Report Oomm. Fish 

 and Fisheries, 1883. 



t The small amount of water which enters the Sigsbee gravitating- 

 trap is one great objection to it. Negative results with this apparatus do 

 not necessarily show that life does not exist at the depth at which the 

 door is opened, and the instrument does not collect from a large enough 

 area for a successful determination of the abundance of life which it is 

 intended to capture. From what has been published, and statements of 

 those engaged in deep-sea exploration, I am led to suj^pose that the 

 " Sigsbee Gravitating- Trap " has given only negative data in regard to 

 the problem of the existence of characteristic nomadic life in intermediate 

 depths of the sea. 



