JEFFERY : ON THE HAIRS OF MOLLUSCA, &C. 23 



All my specimens from the garden ponds, which are any- 

 thing like clean, have been subjected to a scraping and brushing 

 process, while those from the other pond were clean without it. 



The extended, and in many cases, labiate growth seen in 

 these shells, as I have before remarked (J.C., vol. iv., p. 263), 

 occurs in the late summer when the season of reproduction is 

 mostly over, and when we may suppose that the mollusc is 

 endeavouring to ' lay on flesh,' in order to meet the period of 

 fasting through the coming winter, and that expansion of body 

 would require extension of shell is palpable. 



Some of my specimens, it will be seen, have double lips. 

 The second or inner lip is formed in the spring following ; and 

 here we may note that the body probably suffers emaciation 

 through the period of hibernation, and hence the contraction of 

 the home by the formation of the inner lip in the spring. 



Before leaving these ponds I will allude to two specimens 

 of L. auricularia which I have taken in them this past summer, 

 which seem to agree in form with the var. labiata of Z. 

 stagnalis. I send them for exhibition. 



There are two specimens in the South Kensington Museum, 

 from Kashmir, very like them, but I forget if the variety is there 

 named or not. 



I will here bring my paper to a conclusion by calling atten- 

 tion to two errors, as I take them, in published works, with 

 regard to the formation of shells. 



Firstly, Dr. Jeffreys, in his introduction to ' British Con- 

 chology,' p. 48, states on the authority of Mr. E. J. Lowe, re- 

 specting the growth of shells, that ' most species bury themselves 

 in the ground to increase the dimensions of their shells.' 



I cannot help thinking there is some mistake in this state- 

 ment. That many species, H. aspersa for instance, do excavate 

 a hole in the ground and partly bury themselves for the pur- 

 pose of depositing their ova I have had frequent evidence. 

 Mr. Lowe may have been misled by this. 



