Journal of conchology . icallydistributed vary in different individuals from black to the typical grey. Someindividuals answer lo the description of var. uinbrosa, Philippi.—Lionel E. Adams{Read before the Society, November 2nd, 1921). 253NOTE ON GIBBULA PENNANTI Philippi. By A. J. PEILE, (Read before the Society, November 2iicl, 1921). Through the kindness of Mr. J. R. le B. Tomlin I have recently hadthe opportunity of investigating the radulse of Gibbula umbilicalisand G. peuftanii from Guernsey.^ The radute of three individuals of each species have been each set
Journal of conchology . icallydistributed vary in different individuals from black to the typical grey. Someindividuals answer lo the description of var. uinbrosa, Philippi.—Lionel E. Adams{Read before the Society, November 2nd, 1921). 253NOTE ON GIBBULA PENNANTI Philippi. By A. J. PEILE, (Read before the Society, November 2iicl, 1921). Through the kindness of Mr. J. R. le B. Tomlin I have recently hadthe opportunity of investigating the radulse of Gibbula umbilicalisand G. peuftanii from Guernsey.^ The radute of three individuals of each species have been each set the three radulse agree absolutely with one another. There are distinct differences between the two sets which, coupledwith the difierences in shell character, should, in my opinion, qualifypennanti for specific rank. The most noticeable difference is in the outline of the centre tooth,which in pennanti has a top like a flattened ace of hearts with aslender neck below it, whereas in unibilicalis it is broad and almost. flat with a broader neck. The backs of the five laterals also inpennanti are more curved and the cusps are more pointed than inunibilicalis. An attempt to show the salient differences is made inthe appended sketches which show, in each case, the central, the fivelaterals on one side and the first two of the many marginals. The specimens figured will be deposited in the British Museum. The radulai of G. /nagits L., divaricata L. and cineraria L. havea closer resemblance to that of untbilicalis Da. C. than to that ofpennajiti Phil. I Tomlin in /. oj Conchology, vol. 16, p. 236. 254 A MONSTROSITY OF MACTRA STULTORUM Linne. By Dr. W. G. N. VAN DER SLEEN. (Read before the Society, February gth, 1916). In the course of the last three years I have frequently come acrossspecimens of Madra stultorum L. whose shell showed a veryabnormal form. When finding an empty shell of this form the firsttime, I instantly compared it with Mya truncata, but this comparisonis false in
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