297 

 THE SOUTH DEVON RACE OF HYGROMIA LIMBATA (Drap.). 



By H. C. muggins. 



(Read Ijefore tlie Society, December loth, 1919). 



In July, 191 7, Mr. A. S. Kennard was fortunate enough to take at 

 Coonibe in Teignhead, near Teignmouth, three examples of a mollusc 

 which at first sight he referred to H. livibata. Subsequent com- 

 parison, however, with examples of that species from Northern France 

 caused him to have doubts of the correctness of this identification, 

 and as he could not spare the time to visit Devon for more speci- 

 mens, I undertook a special journey, with the result that I obtained 

 abundant material, enabling the question of identity to be settled 

 satisfactorily. This occurrence has already been^ recorded by Messrs. 

 Kennard and Woodward. 



Before dealing with its Devonshire habitat, a short description of 

 the mollusc itself may not be amiss. It is not unlike H. striolata^ 

 but is darker in colour, has longer more delicate horns, and an 

 appearance of almost waxen smoothness and finish lacking in the 

 commoner species ; when crawling among dead leaves the animal 

 somewhat resembles a young Arianta arbiistorum. The texture of 

 the shell is glossy, with a smooth, rather fine striation ; the umbilicus 

 is narrow and deep, and in adult examples is often covered by the 

 reflection of the lip. This species can always be distinguished from 

 any other British Hygrotnia by its smooth even coiling, large reflected 

 mouth, and slight peripheral keel, a feature much developed in young 

 specimens. 



The Devonshire H. liinbata are, on an average, considerably 

 smaller than those found in Northern France, 9x12 mm. being the 

 usual size. They are subject to the usual fluctuations of shape and 

 size, from which several varieties have been selected on the continent, 

 all of which are found in Devon, except, of course, var. major. I 

 have a specimen, 10 x 13! mm., which corresponds to var. major in 

 our Devon race, though smaller than the average examples in many 

 parts of France. Of these, I have noted the following : — 



var. minor Moquin-Tandon. — "Shell smaller, keel more 

 marked." Devon examples, 8 x 10 mm. 



var. trochoides Moquin-Tandon. — " Shell globose, conical." 

 Devon shells, iij x 11 mm. 



var. depressa Mabille. — " Shell globose, depressed, witli very 

 slightly raised spire, and deep sutures." Devon shells, 8 x i2|- mm. 



I Proceedings of the Malacological Society of London, August, 1918. 



