were found to be used for seizing the genital -opening- of the 

 female at the moment when the spermatophore Avas approached ; 

 there was no corresponding action in the case of Chernes S , in 

 which the legs exhibited no marked modification. 



The next Meeting of the Society for Scientific Btisiness will 

 be held on Tuesday, February 20'th, 1912, at half-past Eight 

 o'clock P.M., when the following communications will be made : — 



1. A. T. Mastermax, M.A., D.Sc, F.Z.S. 



i^otes on Age-determination in Scales of Salmonoids, with 

 special reference to Wye Salmon. (With lantern illustrations.) 



H. Lyster Jameson, M.A., D.Sc, Ph.D., F.Z.S. 



Studies on Pearl-Oysters. — I, The Structure of the Shell 

 and Pearls of the Ceylon Pearl- Oyster (Ifargaritifera tndgaris 

 Schumacher), with an examination of the Oestode Theory of 

 Pearl Pi"oduction. (With lantern illustrations.) 



3. Robert Shelford, M.A., F.Z.S. 



Mimicry amongst the Blattidae ; with a Revision of the 

 Genus Prosoplecta Sauss. 



4. The Rev. O. Pickard-Cambridge, F.R.S., O.M.Z.S. 



Contributions to the Knowledge of the Spiders and other 

 Arachnids of Switzerland. 



The following papers have been received : — 



1. Herbert L. Hawkins, M.Sc, F.G.S . 



The Classification, Morphology, and Evolution of the 

 Echinoidea Holectypoida, 



2. H. G. Plimmer, F.R.S., F.L.S., F.Z.S. 



Blood- Parasites found in the Zoological Gardens during the 

 four Years 1908 1911. 



