SCIENTIFIC SOCIETIES. 115 
we occasionally see whitish bands (usually the 2nd and 8rd) on old shells 
caused in this way, because the locality of the bands, even when these are 
absent, is thinner and more easily destroyed than other parts of the shell. 
This phenomenon I have as yet only witnessed in the bandless forms of 
the varieties lutea and lilacina, but I doubt not that it occurs in other 
varieties as well. Another way of demonstrating the bands in an 
apparently bandless specimen is to put it into dilute hydrochloric acid. In 
this way I have produced somewhat transparent bands (No. 3 notably) in a 
specimen of var. lutea which before being so treated showed no traces of 
bands. Ihave not noticed that H. nemoralis is ever eroded in the same 
way, and [ quite failed to get any marked traces of bands with hydrochloric 
acid.—T. D. A. CocKERELL. 
Planorbis glaber in Surrey.— Towards the end of my paper on Surrey 
Mollusca I said that I expected that P. glaber would be found in Surrey, 
and it would seem that these expectations have been already realised, for 
two broken shells which I found in the rejectanenta of the Thames at Kew, 
on December 29th, have been named by Mr. W. D. Roebuck, the Recorder 
of the Conchological Society, as P. glaber. The Paddock Wood specimens, 
however, he considers a variety of P. albus. — ‘I’. D. A. CockERELL (51, 
Woodstock Road, Bedford Park, Chiswick). 
CRUSTACEA. 
Ebalia cranchii at Penzance.—I send by post herewith two specimens 
of Ebalia cranchii. They were dredged in our bay on a fishing-ground 
known to us as the ‘* White Houses,” about two or three miles due south 
of our pier-head, and having a shingly bottom. Several other specimens 
were secured at the same time. I suspect that the presence of this crab 
in large numbers is due to the existence of some unknown law of Nature 
which occasionally causes little crabs of certain species to shoal. I have 
noticed it of Portunus arcuatus once, and of Corystes cassivelaunus many 
times.—Tuomas Cornisu (Penzance). 
SCIENTIFIC SOCIETIES. 
Linnean Society or Lonpon. 
February 5,1885.—F rank Crisp, LL.B., Vice-President & Treasurer, 
in the chair. 
The Rev. L. Klein, B.Se., was elected a Fellow of the Society. 
A paper was read “ On the Arbaciide, Gray” (Part I., the Morphology 
of the Test in the Genera Celopleurus and Arbacia), by Prot. P. Martin 
