iOO JOURNAL OF CONCHOLOGY, VOL. II, NO 7, JULY, I905. 



— a phenomenon that may be of reversionary significance ; one hopes 

 that it will be possible to know exactly how much greater this altitude 

 is by the aid of suitable measurements. 



The fact that o is dominant over 5 not only within the limits of 

 one species but also when the o character is borne by one species 

 and the 5 is borne by another, suggests a line along which a closer 

 knowledge of the nature of unit-characters may be sought. The 

 application of the knowledge acquired by Lang's experiment with 

 H. hortensis and H. nemoralis to Coutagne's observation is very sug- 

 gestive, for it shews how necessary . to a naturalist who aims at 

 interpreting his observations in the field is the knowledge acquired 

 by experiment in the laboratory. 



In conclusion, I express my thanks to Mr. R. Standen for giving 

 me the benefit of his conchological knowledge, and to Mr. E. Collier 

 for giving me the opportunity of examining his collection of Helix 

 nemoralis. 



Additions to the Land and Freshwater MoIIusca of Northamptonshire. 



— Acictda lineaia, February 22, 1898, a single living specimen in a rotten elder 

 stump in Maidwell Dales. Vertigo substriata, March 24, 1903, several living 

 specimens from a small colony at Haselbeech ; the habitat is in a withy bed amongst 

 the fallen leaves, dead rushes, and moss. In March, 1904, I found several dead 

 shells in company with V. ptisilla in the rejectamenta of the river at Cranford, close 

 to a similar withy bed. Ena inontana, a single dead specimen at Stanwick, 

 Oct. 22, 1904. Aplecta hypno'iini, May 14, 1904, close to Castle Ash by station ; 

 smaller specimens, not plentiful, in Sulby Reservoir, in Sept., 1903. Linimza 

 pereger, a pretty lineated form from Naseby Reservoir. Sphceriiiin pallidum, 

 July 16, 1904, one specimen at Far Cotton, two near Blisworth station. Pahides- 

 trina jenkinsi, July 16, 1904, two specimens in the canal near Blisworth station. — 

 [Rev.] W. A. Shaw {Read before the Society, March 8, 1905). 



Hydrobia jenkinsi in Rivers.— A young conchologist, Mr. Cecil Birts, of 

 Welling, sends me for identification specimens which are undoubtedly H. jenkinsi. 

 The point of interest is that they were found by him in the Cray at Crayford, about 

 three or four miles above where the Cray joins the Thames. The river is fairly 

 rapid and is a clear chalk water. The shell, therefore, seems to be ascending from 

 brackish into fresh water, and I do not think it has been noticed so far away from 

 estuaries— at any rate in Kent, where it was first determined. — [Rev. Canon] J. W, 

 HORSLEY {Read before the Society, May loth, 1905). 



Vertigo substriata (Jeff.) m. sinistrorsum. —Amongst a number of Vertigo 

 substriata, collected in 1898, at Shipley Glen, Yorks. , by Mr. Fred Booth, one 

 full-grown sinistral example occurred, which remained unnoticed until quite recently 

 when Mr. J. Wilfrid Jackson, on looking over the set, detected this great rarity. 

 This makes an interesting record, as I am not aware of any prior instance of sinis- 

 Uorsity in this species. — K. Stajnden {Read before the Society, May lolh, 1905). 



