162 Reviews and Book Notices. 
Rhizocarpon confervoides D.C.—On sandstone wall tops, 
Benty Lee. Scarce. 
Rhizocarpon obscuratum Mass.—Sandstone wall tops, Har- 
den Moor. Not common. 
Verrucaria hydrela Ach.—On submerged stones in stream, 
Cullingworth, very similar to JV’. aquatilis but larger spores. 
Plentiful. 
Verrucaria macrostoma var. aphanostoma S. & H.—On 
mortar, wall tops, sandstone, Cullingworth, Manywells Road. 
Not common. 
Verrucaria muralis Ach.—On mortar, wall tops, sandstone, 
in all the district. Common. 
Polyblastia intercedens S6m.—On mortar, wall tops, sand- 
stone, Manywells Road near quarries. Common. 
Ors 
Pond Problems. By E. E. Unwin. Cambridge University Press, 
120 pages, 2s. This is one of the Cambridge Nature Study Series edited 
by Mr. Hugh Richardson, and contains a number of interesting chapters, 
prepared for the use of scholars, and the volume is well illustrated. Among 
the subjects dealt with are: ‘How to obtain specimens’; ‘ What is 
an Insect ’; ‘ Breathing Water Beetles and Water Boatmen’; ‘ Diving 
Tubes and a Diving Bell’; ‘Locomotion ’; ‘ Life Stories’; ‘ From Egg 
to Imago. 
Essays Towards a Theory of Knowledge. By A. Philip. London: G. 
Routledge, 126 pages. The author asks: ‘ When we find Science, which 
has done so much and promised so much for the happiness of mankind, 
devoting so large a proportion of its resources to the destruction of human 
life, we are prone to ask despairingly : “Is this the end?” If not, how 
are we going to discover and assure for stricken humanity the vision and 
the possession of the Better Land?’ and he deals with the subject in four 
chapters, the headings of which are: ‘Time and Periodicity’; ‘ The 
Origin of Physical Concepts ’; ‘ The Two Typical Theories of Knowledge ’ ; 
“The Doctrine of Energy.’ 
The Determination of Sex. By L. Doneaster. Cambridge University 
Press, 172 pages, 7s. 6d. net. In this work Dr. Lancaster brings together 
some information which he intended to include in a second edition of his 
Heredity in the Light of Recent Reseavch. As time went on, however, 
advances in knowledge altered his plan. The present book discusses the 
more important lines of evidence which bear on the problem of sex-deter- 
mination, and he illustrates each with representative examples. Full 
reference to literature enables the reader desiring further information on 
any given point to readily obtain it. The work deals entirely with the 
question so far as it relates to animal life. The frontispiece is an excellent 
coloured plate of a Gynandromorph Bullfinch, and among the other 22 
plates we notice the following: ‘ Life Cycle of the Gall Fly’; ‘ Abraxas 
gvossulaviata (Currant Moth) and its variety Jacticolor’; ‘ Sex-limited 
Transmission of barred pattern in Fowls’; ‘ Pedigrees of Sex-limited 
Affections in Man (Colour-blindness and Haemophilia)’; ‘ Spermato- 
genesis of Ascaris’; ‘Spermatogenesis of the Hornet’; ‘ The Parasite 
Sacculina and its Effects on its Host’; ‘Gynandromorphic Moths pro- 
duced by crossing two species of the genus Lymantria’ ; and Chromosome 
Cycle in the worm habdonema.’ These titles alone give an idea of the 
far-reaching character of the book. 

Naturalist 
