274 



ON SOME KEMARKABLE SHELL MONSTROSITIES.^ 

 Ey G. C. RoBsoN, B.A. 



Bead 8th November, 1912. 



Most coiicholojiists are familiar with tlie phenomenon of the formation 

 of callous projections on the inner surface of the valves of Lamelli- 

 branchs as a reaction a<?ainst foreign hodies introduced between shell 

 and mantle. The following note deals with two growths apparently 

 of this nature which are admitted hy those who have examined them 

 to be unique specimens of their kin<l. One of them is from the 

 British Museum Collection, and the other from the Museum of the 



Fig. 1. Natural size. 



Royal College of Surgeons. Tlie author is indebted to ^Fr. R. H. 

 Burne, Assistant Conseivator of the latter Institution, for the loan of 

 the second specimen and for inf(U'mation coiieeruing it. 



These growths were in both instames impei'fectly registered. It is 

 thus impossible to refer them with absolute certainty to ;iny particular 

 form. The British Museum example (Fig. 1) was acquired over half 

 a century ago, and was presented by someone who could give no 



' Published by peiniission of the Trustees of the British Museum. 



