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A SPECIMEN OF LIMN^A PEREGER COILED ON THE FLAT^ 

 By Dr. A. E. Boycott, F.R.S. 

 Read 9th June, 1922. 

 A PAIR of sinistral Limncea pereger, derived ultimately from the 

 classical locality near Leeds, which I owe to the kindness of Mr. J. W. 

 Taylor, M.Sc, produced in 1B20 a brood of 350 sinistral offspring. 

 A pair of these were put in a jar by themselves when quite small 

 on 4th November, 1920. Eggs were seen on 24th May, 1921, and 

 when the brood was sorted out and examined carefully on 12th July, 

 1921, I found twenty-eight sinistral young, three dextral, and one 

 which was coiled on the flat. At this time it was about 2 mm. 

 in diameter. With a jar to itself it grew fairly quickly, and by the 

 autumn was about 8 mm. in its greatest diameter. It started growing 

 again the following April, and did well till 5th June, 1922 ; in the 

 morning it seemed quite well, but my hopes of a self-fertilized 

 progeny were doomed to disappointment, for in the afternoon it 

 was found out of its shell, dead. 



IS m* 



The shell is shown from the side in Fig. A, dorsally in B, 

 and ventrally in C. It is coiled very nearly on the flat ; indeed, the 

 appearance of a slight inclination to coil in a very extended sinistral 

 spiral is due to an obliquity of the growth of the lip, which appeared 

 in the spring growth of 1922. The coil is mostly but not entirely 



