312 Notes and Comments. 
the United Kingdom, to request particulars as to what is 
being done in the direction indicated, and to ask if the above 
information may be embodied in the Return.’ Apparently 
there were difficulties with regard to the provincial institutions, 
but, with slight alterations, the motion was agreed to and 
ordered accordingly. Personally, we feel strongly that there 
is much educational work to be accomplished on the lines 
suggested by Lord Sudeley, and the public would gladly 
avail themselves of such guidance. The difficulty, however, 
is likely to be due to the fact that most provincial institutions 
at present are short of funds, and understaffed. 
CLASSIFICATION OF IGNEOUS ROCKS. 
In addition to its Annual Report and List of Members, the 
Birmingham Natural History and Philosophical Society has~ 
issued two separate papers, viz., ° Classification of Igneous 
Rocks,’ by Dr. H. Warth, and ‘ Introduction to the Fauna 
of the Midland Plateau,’ by Mr. P. E. Martineau. In his 
paper Dr. Warth refers to his previous suggestions of a chemical 
classification which were founded upon the ordinary chemical 
composition of the rocks and not on moleculars. The latter 
would have afforded little advantage as long as he partitioned 
by individual bases only. ‘In the following method I have, 
however, based the partition not upon individual bases but 
upon the respective sums of bases of equal valency, and in 
this case molecular percentage is required and yields superior 
results. . . . One thousand rocks were selected from current 
literature and their molecular percentages calculated in the 
usual manner. A dichotomous division was then carried out,’ 
etc. Diagrams and tables innumerable follow, to which we 
must refer our readers who may be interested. 
EVOLUTION OF THE ARROW. 
The Journal of the East Africa and Uganda Natural History 
Society,* besides containing many interesting notes and illus- 
trations bearing upon the larger mammalia, etc., of the districts 
covered by the title of the publication, contains an interesting 
paper on ‘ The Evolution of the Arrow,’ by Mr. C. W. Hobley. 
By a series of illustrations the author shows the development 
of the arrow point from a mere stone splinter, through various 
stages, to the fully-barbed stone arrow-point. He then refers 
to the arrow-head mimetic of Acacia thorn, through various 
stages, to the ‘Monbuttu arrows with extravagant barbing.’ 
Then follows an arrow-head of iron, obviously a copy of a 
stone arrow-point, and so on. Similarly, the evolution of the 
‘feathering’ is shown from a leaf, and piece of leather, to 
the most elaborate system of feathering. ‘The most highly- 
* Vol. III., No. 6, July 1913. 72 pp- Longmans, Green_& Co., 5s. 4d. 
Naturalist, 
