ZOOLOGICAL AND BOTANICAL ASSOCIATION. 243 



oasy to account for : but it is certainly a great advantage to the Ni- 

 phargi, in securing to them both a higher and more equable tempera- 

 ture than they could otherwise by any possibility enjoy. The tempera- 

 ture of the water in the Corsham pump (whose depth is supposed to be 

 about thirty feet) averages 46°, while that of the well at Bingwood is 

 a& high as 50° F., even when there is ice on the water above ground. I 

 ascertained also, by experiment, that exposure to a colder temperature 

 had the effect of very soon numbing and deadening the vitality of 

 Niphargi. While they lived in my possession, which was for several 

 weeks, it was necessary to keep them in a warm room. 



The depth of the Ringwood pump I could not ascertain ; but it was 

 sunk only about fourteen years since, and has, probably, some connex- 

 ion underground with an old well a few feet distant, which is now 

 covered over with earth, and cannot be examined. Upon making in- 

 quiry about other wells at Ringwood, though unable to procure addi- 

 tional specimens, I found out that Niphargi had been seen before, but 

 only in the purest water, and not, it would seem, in that (as some of 

 the water is at Ringwood) inhabited by other visible organic forms. It is 

 likewise reported of the well at Corsham, which is about two hundred 

 years old, that, some thirteen years ago, large numbers of Niphargi were 

 raised by the pump, though of late the supply appears almost exhausted. 

 Their appearance has not been confined to any particular season ; they 

 have been found at Corsham both in summer and winter, occasionally ; 

 at Ringwood, however, they have not been searched for, except in winter, 

 as yet ; and specimens could not generally be obtained from the well to 

 which I had access, unless the water were pumped up in large quan- 

 tity early in the morning, when the spring had lain undisturbed during 

 the previous night 



The two localities differ considerably as to the nature of the ground. 

 Corsham stands high, being on a bill, at least six hundred feet above 

 the level of Bath ; Ringwood, on the contrary, lies very low, is close to 

 a wide- spreading river, and surrounded by a considerable extent of flat 

 country. Corsham is on the oolite formation, Ringwood on a chalk- 

 flint gravel. It is, therefore, natural that we should find a decided 

 variation between the individuals of the same species (as in N.f&ntanus) 

 found in each locality. 



In concluding, I must express a hope that the facts now detailed 

 will lead to a thorough investigation of the history and distribution of 



