DECEMBER 25, 1913] 
The subject is rather intricate, as may be judged 
from the history of the genera Uruguaya, 
Carter, 1881, and Potamolepis, Marshall, 1883. In 
describing the latter, Marshall, it appears, con- 
fessed that its separation from Uruguaya depended 
only on a geographical consideration, one group 
being found in Africa, the other in South America. 
Yet now they are assigned to separate subfami- 
lies. Dr. Annandale, however, admits that the 
recognition of his sub-family Potamolepidine “‘ de- 
pends to some extent on the fact that no gemmules 
have been found in any species that can be defi- 
nitely assigned to the genus Potamolepis,” and 
that if in the future “gemmules be found in an un- 
doubted Potamolepis with specialised gemmule- 
spicules that can be called microscleres, the genus 
would have to be transferred to the Spongillinz.” 
It is evidently a case in dealing with which the 
student must be specialised as well as the spicules. 
It will not interest the water board at Cardiff, 
which is reported to have cleared its pipes of a 
blockading sponge-growth simplv by using a solu- 
tion of common salt, without reference to system- 
atic nomenclature. 
As it is sometimes supposed that the influence 
of environment is all-suficing for the origin of 
species and makes natural selection a needless 
hypothesis, it is worth while to quote Dr. Annan- 
dale’s remark that “it is not unusual for two 
species that live together to adopt diametrically 
opposite means to attain the same end.” This he 
illustrates by the case of Cortispongilla barroisi, 
notable for the possession of a well-defined and 
almost symmetrical central cavity, while Nudo- 
spongilla aster, which inhabits the same environ- 
ment, is a peculiarly compact sponge without any 
trace of a central cavity. The explanation offered 
is, that “if the particularly well-developed exhalent 
system implied in the production of a central cavity 
opening by a large osculum is advantageous in 
getting rid of silt that has entered the sponge, a 
compact structure may be equally efficient in pre- 
venting the silt from entering at all.” 
In separate sections of the report several sub- 
jects besides sponges are discussed by Dr. Annan- 
dale and his collaborators, but to these justice 
cannot be done within the limits of this notice. 
T. R. R. STEpBInc. 
PROF. P. V. BEVAN. 
“eae younger generation of Cambridge physic- 
ists and many others will have noticed with 
regret the announcement in last week’s NATURE 
of the death of Prof. P. V. Bevan at the early 
age of thirty-eight. He had a distinguished scien- 
tific record, and his friends confidently expected 
for him a useful and fruitful career. Entering 
Cambridge University in 1896 he took up the study 
of mathematics, and in 1899 was fourth Wrangler. 
The following year he was placed in the first 
division of the first class in part ii. of the mathe- 
matical tripos. With this equipment he turned his 
attention to experimental physics, and commenced 
research in the Cavendish Laboratory under Sir 
J. J. Thomson. In 1901 he was appointed to a 
NO. 2304, VOL. 92 | 
NATURE 
481 
demonstratorship, to which lecturing duties were 
added in 1904, and in 1908 he became Professor of 
Physics at the Royal Holloway College, a post 
which he held till his death. 
Prof. Bevan’s earliest important research was 
a very complete investigation of the action of light 
on the rate of combination of hydrogen and 
chlorine, but after his removal to London he 
devoted himself to optics. Starting from the work 
of Prof. R. W. Wood on anomalous dispersion in 
sodium vapour, he extended it to the vapours of 
other alkali metals. He made a detailed study of 
the absorption spectra of the vapours of lithium 
and cesium, mapping their principal lines, and 
testing the applicability of the various formule 
suggested by Kayser and Runge, Rydberg, and 
Hicks to the series of lines in these spectra. Both 
at Cambridge and in London Bevan was: keenly 
interested in the religious life of the students. 
He was president of the Cambridge Nonconformist 
Union, and later took an active part in the student 
Christian movement, to the publications of which 
he was a contributor. His was a strong, vigor- 
ous, and genial personality, which won the affec- 
tion of all the students with whom he came into 
personal contact. A. W. 
NOTES. 
For several days Sir David Gill has been suffering 
from double pneumonia at his residence in Kensing- 
ton. As we go to press we learn that though his 
lungs are improving and he maintains his strength, 
his condition is still critical. 
Dr. Trempest ANDERSON, whose death was 
announced in Nature of September 4, has left 50,o00l. 
to the Yorkshire Philosophical Society, of which he was 
formerly president, and 20,0001. to the Percy Sladen 
Memorial Fund, established by his sister, Mrs. Sladen, 
in 1904. 
Ir is proposed to present to the Royal Society a 
portrait of the retiring president, Sir Archibald Geikie. 
A small executive committee, with Sir William Ram- 
say as chairman, has been formed to carry out the 
preliminary arrangements and collect subscriptions, 
which it is agreed should range between one and 
three guineas. Promises amounting to about one 
hundred guineas have been received already from fifty 
fellows of the society. Subscriptions may be sent to 
the treasurers of the Geikie Portrait Fund, at the 
Royal Society, or paid direct to Messrs. Coutts and 
Co., 440 Strand, W.C., for the fund. The subscribers 
will constitute a general committee, and they will be 
called together at a later date to consider the choice 
of an artist and other matters. 
TuE valuable services rendered to public departments 
by the Royal Society were referred to by Sir Archibald 
Geikie in his recent presidential address (see NaTuRE, 
December 4, p. 405); but it was pointed out that 
though the society has acquired the character of a 
kind of central bureau of science, there has been no 
corresponding increase of financial support. Sir 
Joseph Larmor, in The Times of December 20, refers 
