2 2 JEFPERY: ON THE HAIRS OF MOLLUSCA, &C. 



Having recently had an opportunity of seeing the general 

 or foreign portion of the conchological department (which is all 

 that is at present on view) in the South Kensington Museum, I 

 noticed that in several families we have spine-like formations of 

 considerable proportions which appear to be of a shelly nature, 

 and may be compared with the spines proper of the botanist, 

 e.g., the Muricidse, Neritinidse, Trochidae, Tridacinidae, Pinnidse, 

 and notably Spondylidse. These spines no doubt have their 

 uses, but I should only be getting farther out of my depth 

 were I to hazard an opinion as to what they may be. 



The whole question of the formation and uses of the 

 shells of our mollusca, from the rudimentary internal form as 

 seen in the Cuttle and the Slug, to the handsome shell-homes 

 which we see allotted to others, is well worthy of investigation 

 by the conchologist. The abnormal forms of our common 

 shells and the reasons and causes which lead to the change of 

 form, together with the variable bandings and other markings, 

 should engage the attention of those who have the opportunity 

 with regard to elucidation. 



Two small artificial ponds in my garden have produced 

 some interesting forms of LimncEa auricularia and L, stagnalis, 

 some of which I exhibit this evening, others have been shown 

 before. 



The latter species (from the same stock) has quite a 

 different form of shell when grown in another pond, as will be 

 seen by my examples. The garden ponds are, without doubt, 

 supplied with water from our chalk hills, and conveyed some 

 distance by an iron pipe, while the other water is from another 

 spring, which I think fnay be derived from our clay hills. 



The shells in the garden ponds are generally coated thickly 

 with a lime deposit from the water, on which deposit there may 

 often be seen a lengthened confervoid growth, which sometimes 

 entirely impedes the progress of the snail, occasionally causing 

 its death. 



J.C., v., January, 1886. 



