PREFACE. 
The Zoological descriptions and de- 
terminations, both in “The Depths 
of the Sea” and in this preliminary 
sketch of the proceedings of the 
Challenger, must be regarded as, to 
a certain extent, provisional. Some 
of the more remarkable and novel 
forms have been selected for illustra- 
tion to give a general idea of the fa- 
cies of deep-sea life; but the amount 
of new material is very large, and it 
will take some years of the patient 
work of many hands, with full ac- 
cess to libraries and collections, to 
bring it into order. 
As in “The Depths of the Sea,” 
the metrical system of measurement 
and the centigrade thermometer scale 
are employed in these volumes. In 
case the centigrade notation should 
not be familiar to all my readers, I 
introduce a comparative scale, em- 
bodying those of Fahrenheit, Celsius 
(Centigrade), and Réaumur, for ref- 
erence.* 
With few exceptions, the illustra- 
tions are from drawings by Mr. J. J. 
Wild; and, as in the former volume, 
I have to give my best thanks to Mr. 
* 1° Fahrenheit = 0°55° C. = 0°44° R. 
1° Centigrade = 0°80° R. = 1:80° F. 
1° Réaumur = 1°25°C. Pd ser Ne 
