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NOTE ON HYGROMIA HISPID A, VAR. NANA, JEFF. 

 By the Rev. E. W. Bowkll, M.A. 

 Read 12th March, 1915. 

 Mr. Kennard recently pointed out to me a shell in my collection as 

 a typical example of this form, which is said to be equivalent to 

 II. nebulata, Menke. The specimen was taken at Leatherhead, and 

 is now exhibited. Height 4 mm., major diameter 7"1 mm. 



The genitalia showed four simple digitate glands on each side. 

 Typical hispida may show six on each side, but it will generally be 

 found that these are disposed in groups of two, so that they would 

 be better described as three double digitations. I find, however, 

 that there is considerable variation in the number of the glands, 

 large specimens tending to possess more glands and more branching. 



The radula, of which a sketcli is here submitted, is 1*8 mm. long 

 and 65 mm. wide. There are 88 rows of unci, distributed according 

 to the formula 13. 10. 1. 10. 13. The more external adraedians tend 

 to become larger until the last two are reached, and these are very 

 similar to the externals. The most striking feature about the radula 

 is the length and narrowness of the mesocones, except in the external 

 region. I do not find anything similar in young examples of typical 

 hispida, while in adult specimens there is a marked tendency to vary 

 in the opposite direction. In the present specimen the cones of the 

 external unci are more than usually short ; variation in this respect 

 is common in hispida, but it is much more usual to find prolongation 

 of these cones in the smaller examples. 



I refrain from giving measurements of these small structures, 

 because I do not yet possess a series mounted in balsam, and the 

 triiil measurements of glycerin jelly preparations have proved un- 

 satisfactory, owing to the relatively high numerical aperture required 

 to produce sharp outlines at the necessary magnification. 



It seems possible that II. nebulata may be another of these barely 

 distinct small Helices, and it may be worth while for those who 

 have the opportunity to pay special attention to its economy and 

 distribution. 



VOL. XI.— JUNE, 1915. 



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