156 The Irish Naturalist July, 
esker-moraine substance of the newer drift as typified by the Central 
Plain of Ireland, but so far as we can see offers no explanation of the 
difference. 
In the chapter on the glaciation of Europe attention is again directed 
to the contrast between the older and newer drifts particularly as regards 
the fact that the loess and the remains of Palaeolithic man are confined to 
the surface of the former. There follows an excellent and most readable 
account of the stages of retreat of the ice, and of the relative levels of the 
sea at the different stages. The Quarternary Mammals and Man each 
form the subject of a chapter, and the various theories of the Ice Age 
receive full and lucid treatment. This portion of the work includes an 
extremely interesting discussion of the isostatic theory and its adequacy 
to explain the facts relating to the warped shore -lines of North America, 
and the raised beaches and submerged forests of Northern Europe. Post- 
glacial changes of climate also receive attention, and the volume concludes 
with an attempt to correlate the various sub-divi.sions of the American 
Drifts with those of Europe. 
As regards the cause of the Ice Age, we are left as much in the dark 
as ever. It must be admitted that, among the theories that have been 
brought forward to account for the phenomena of the Ice Age, there is 
not a single one which meets the facts of the case in such a manner as to 
inspire confidence. 
In conclusion, we congratulate Mr. Wright on having produced a 
most important contribution to the literature of Pleistocene geology, 
and one which cannot fail to stimulate interest and activity in that most 
fascinating field of research. 
A. R. D. 
GANNETS. 
The Gannet — A Bird with a History. By J. H. Gurney, F.2.S. London J 
Witherby and Co., 1913. Pp. lii. -f- 568. Price 15s. 
This bulky and weighty volume of about 620 pages, including index 
and historical preface, is full of information, and although there are 4i 
pages of " Notanda and Corrigenda," it is carefully written. At any 
rate there is evidence of a desire to be accurate. The book is illustrated 
with over 120 photographs, some very interesting, and maps. It is 
divided into 22 chapters, the first two of which deal with the names of 
the Gannet, and its distribution. There are 8 chapters on its various 
breeding -places, and the remaining 12 chapters treat of its numbers, 
nidification, nestlings, habits, food, flight, mortality, ag'e, plumage, 
osteology and anatomy. To those who enjoy reading a monograph full 
of extracts, ancient as well as modern, and giving the latest information,, 
the work is bound to remain for years to come an invaluable storehouse 
ior reference. We are told that the nesting-places are all on islands, 
and that the difference between the colour of the young and of the adult 
IS greater than in almost any other bird. 
