i65 



ON THE SUPPOSED OCCURRENCE OF^ 

 JAMINIA TRIPLICATA Studer IN SUFFOLK. 



By J. DAVY DEAN and J. R. le B. TOMLIN, M.A. 



(Read before the Society, June 7th, 1916). 



In 1906 the late Dr. Chaster Introducad^ yam/nia tripiicata Studer as 

 "a new British terrestrial mollusc" on the strength of specimens 

 which he had collected at Brandon in Suffolk. The record was 

 icceived with a certain amount of doubt at the time and has never, 

 so far as we know, been subsequently confirmed. 



Through the kindness of Dr. AV. Evans Hoyle, the Director of the 

 National Museum of Wales (which institution now possesses the 

 Chaster Collection of Shells), we have been able to examine and 

 compare the original specimens on which Dr. Chaster based his 

 record with examples in our own i)rivate collections. We have also 

 received further examples, indistinguishable from this series, from the 

 original locality, through the kindness of Mr. Mayfield, of Mendlesham, 

 who also informs us that it was to this form he referred in his note on 

 "Two and three-denticled forms oi Jaminia muscoriwi T.."^ 



Messrs. Kennard and Woodward in their^ "List of British Non- 

 Marine MoUusca" (19T4) refer the Brandon specimens to P. muscorum 

 var. ^//V Westerlund,^ and remark: — "The British examples referred 

 to P. tripiicata we consitier varietal examples oi P. musconan." 



There is thus in the identification the element of doubt, but before 

 giving, what seems to us, a correct analysis of the subject, we feel we 

 cannot do less than pay a ready tribute to Dr. Chaster's generally 

 accurate determinations. 



What strikes one at once is the absurdity of calling the Brandon 

 shells "remarkably small yi?/// ////>." In our experience any batch of 

 /". imiscoruin will show considerable variation in size, and we find the 

 so-called tripiicata Qni\x<t\y comparable in these extremes of measure- 

 ment with series oij. fiiuscoru/n from — for instance — the Channel Isles, 

 the Berkshire downs, the Isle of Man, Sweden and the United States. 



The Brandon shells are, generally speaking, lighter in colour than 

 typical inuscoruiii—?i point which Dr. Chaster, curiously enough, does 

 not mention. This lighter colour is consistent with a more solid shell 

 and tooth development is correlative. Some are bidentate, while 



1 /. of Conch. ^ vol. xi., p. 319. 



2 /. of Condi., vol. xii., p. 317. 



3 Taylor and Francis, Red Lion Court, Fleet Street, E.C. 



4 Nachrichtsblatt, 1893 (Jul. -Aug.), p. 120, Yorkshire (J. Ponsonby). 



