PREFACE. 1X 
the distribution of living beings, and have of late 
been brought into so great prominence by Dr. Car- 
penter, that it has been impossible for me to avoid 
giving my earnest consideration to their eeneral 
bearings on Physical Geography, and forming decided 
opinions, which, I regret to say, do not altogether 
coincide with those of Dr. Carpenter. The chief 
points on which my friend and I ‘agree to differ’ 
are discussed in the chapter on the Gulf-stream. 
It was at first my intention that appendices should 
be added: to the different chapters, containing lists 
and scientific descriptions of the animal forms which 
were observed. This it was found impossible to ac- 
complish, chiefly on account of the large number of 
undescribed species which were placed in the hands 
of the experts who undertook the examination of the 
several groups. I am not sure that, even if it had 
been possible to furnish them in time, such lists 
would have been altogether an appropriate addition 
to what is intended merely as a popular preliminary 
sketch. 
The metrical system of measurement, and the 
centigrade thermometer scale, have been adopted 
throughout the volume. The metrical system is pro- 
bably familiar to most of my readers. In ease the 
centigrade notation, which comes in very frequently 
owing to the frequent discussion of questions of the 
distribution of temperature, should not be equally 
familiar, a comparative scale, embodying those of 
