20 BULLETIN OF THE 
populous stratum of the ocean, it is evident that no great degree of ac- 
curacy in determining the bathymetrical range of the pelagic fauna could 
be claimed for this method of towing. From the mode of making the 
observations, the catch of all the hauls must have contained representa- 
tives of the fauna of the upper belts of water, regarding the geographical 
range and the composition of which we know as yet but little. 
OBSERVATIONS ON THE PevaGcic Fauna BY THE ‘ BLAKE.” 
In spite, however, of the objections urged above, both Murray and 
Studer contended that, in addition to the deep-sea and pelagic faune, 
there was what might be called an intermediate fauna with character- 
istic species, having nothing in common with the other two, while I 
maintained, on the other hand, from my experiments in the “ Blake,” 
that there was no such intermediate fauna, but that the pelagic fauna 
might descend to a considerable depth during the daytime to escape the 
effects of light, heat, and the disturbing influence of surface winds, and 
that this surface fauna on the Atlantic side of the United States, off 
shore in deep water, did not descend much deeper than 150 to 200 
fathoms, or some point not far distant from that level, depending of 
course to some extent upon the latitude of the observation ; the lower 
bathymetrical limits of the pelagic fauna very probably coinciding with 
the limits to which the action of the heat of the sun, of light, and of 
other disturbing elements of the surface extended. 
The experiments I made on the “ Blake”? were carried on with the 
Sigsbee gravitating trap, which worked successfully, and tested the con- 
tents of a vertical column of water of any desired height. The only 
drawback of the original apparatus was its small size. The machine 
subsequently used by Hensen for his quantitative experiments worked 
on the same principle, of filtering the whole of a vertical column of 
water, and examining the results, 
OBSERVATIONS ON THE PeLacic Fauna By THE “ VEeTTOR PISANI.” 
The next observations made were those of the “ Vettor Pisani.’ 2 
Lieutenant Chierchia devised a net which he asserted could be sent down 
1 Bull. Mus. Comp. Zool., Vol. VI. Nos. 8 and 9, and Three Cruises of the 
Blake, Vol. I. p. 36. 
2 G. Chierchia, Collezioni per Studi di Scienze Naturali fatte nel Viaggio intorno 
al Mondo dalla R. Corvetta Vettor Pisani, Commandante G. Palumbo. 1886. 
