520 Reviews—-The Geology of Anglesey. 
and the author’s already published theory of the origin of the Menai 
Strait brings the stratigraphical portion of the memoir to a close. 
The contents of the remainder of the second volume have already 
been outlined. 
In the course of this review no mention has yet been made of 
the assistance received by the author from other workers. All the 
fossil identifications are the work of specialists, of whom Miss Elles 
also contributes an essay on the graptolite sub-faunas, and in the 
field much help has been rendered by the fossil collectors of H.M. 
Geological Survey ; Mr. J. O. Hughes has carried out a large number 
-of rock analyses, and several distinguished petrologists have lent 
their aid on special points. All this and much other assistance is 
duly recognized by the author, who is throughout meticulous in his 
acknowledgment of help received. 
The memoir is well illustrated, most of the 346 clear text-figures 
are from Mr. Greenly’s own pen, while of the 60 plates the greater 
number are reproductions of photographs taken for H.M. Geological 
Survey, and of the usual excellent quality ; a few are less satisfactory 
and a number of the collotype plates of rock-sections are dis- 
appointing. There are also seventeen folding plates, mainly 
horizontal sections, but including also some coloured reproductions of 
the original field maps, a welcome innovation which will be of 
great value to the field geologist and serves to demonstrate the 
detailed precision of the author’s mapping. 
Accompanying the memoir is a colour-printed geological map of 
Anglesey upon the one-inch scale, which possesses certain advantages. 
Portions of several sheets of the ordinary issue have been combined 
to form a single sheet covering the whole island and a number of 
additional place-names mentioned in the text have been inserted. 
The reduction of the geological boundaries from the six-inch to the 
one-inch scale seems to have been well done, and the common error 
of inserting too much detail has been wisely avoided. The colour 
model, too, has been skilfully prepared and shows the various 
formations to advantage. But the general appearance of the map, 
and what is more, its utility to the geologist, suffers greatly from the 
bad reproduction of the outline. There seems to be an impression 
at Southampton that in a map of this kind only the colours matter 
and that the printing of the topographical detail is of secondary 
importance. Every field geologist knows the contrary. In the 
present map the colour printing 1s adequately done, though the tint 
given to the Ordovician on the map hardly corresponds with that 
shown on the legend. But the outline plate is bad, the printing of 
the title “ Anglesey ’’ shows this glaringly, all the lines are thick 
and lacking in sharpness, the contours are invisible, the smaller 
place-names all but unreadable, while the muddy grey tint which 
has been used in the printing to conceal these defects hinders the 
discernment of the topography under its coating of colour one 
makes it difficult to follow the author’s descriptions. 
