253 

 NOTE ON GIBBULA PENNANTI Philippi. 



By Lt. -Colonel A. J. PEILE, R.A. 



(Read before the Society, November 2iicl, 1921). 



Through the kindness of Mr. J. R. le B. Tomlin I have recently had 

 the opportunity of investigating the radulse of Gibbula umbilicalis 

 and G. peuftanii from Guernsey.^ 



The radute of three individuals of each species have been mounted. 

 In each set the three radulse agree absolutely with one another. 



There are distinct differences between the two sets which, coupled 

 with the difierences in shell character, should, in my opinion, qualify 

 pennanti 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 a 

 slender neck below it, whereas in unibilicalis it is broad and almost 



flat with a broader neck. The backs of the five laterals also in 

 pennanti are more curved and the cusps are more pointed than in 

 unibilicalis. An attempt to show the salient differences is made in 

 the appended sketches which show, in each case, the central, the five 

 laterals 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. have 

 a closer resemblance to that of untbilicalis Da. C. than to that of 

 pennajiti Phil. 



I Tomlin in /. oj' Conchology, vol. 16, p. 236. 



