l80 JOURNAL OF CONCHOLOGY, VOL. 15, NO. 6, APRIL, 1917. 



Surely this form wants naming or re-naming? LiUorina rtidis var. 

 Jiigosa Mont, can be found upon any sea-shore where the type is 

 plentiful, whereas this variety (or is it a distinct species ?) is only 

 found facing the Atlantic and at considerable heights above the sea- 

 level. 



Littorina rudis (Mat.) in some form or other is to be found on all 

 of our shores, and as the varieties Icevis Jeffreys and tenebrosa Mont, 

 in most brackish waters also, where the size of their shells seems to 

 vary in proportion to the salinity of their environment, i.e., the larger 

 the shell the more saline is the brackish water. 



Hence it is a question whether the form under discussion is a true 

 Littorina rudis, or not. However, if we admit the var. tenebrosa 

 Mont, environment can do anything, and so, undoubtedly, I would 

 say it is only a variety, which variety I propose to name var. alticola, 

 and thus to indicate its life high above sea-level. 



At a casual glance this var. alticola might be taken for a sickly 

 Littorina littorea L. As compared with average sized L. rudis, the 

 shell is large, and usually black, but from exposure becomes often 

 very much weathered. All colours are to be found to white, and the 

 shells are often banded. The shells of all specimens are thin, with a 

 long-pointed spire, heavily ridged. The body-whorl is similarly 

 ridged, but in some large specimens wears smooth. The ridges, 

 especially those on the spire, seem to be a life-preserving feature, as 

 they prevent the mollusc from being easily rolled away from the 

 ledges and crevices of the rocks. 



Pisidium lilljeborgi in Carnarvonshire. — At the risk of being tedious I 

 write to record two additional stations for Pisidinni lilljeborgi in the Snowdonian 

 Mountains. During the summer of 1916 I found it in plenty in Marchlyn Bach 

 (i,5S7 feet), under the northern spur of Elidir Fach, and took several specimens in 

 Llyn Peris (340 feet), the upper of the two Llanberis lakes. In a previous note on 

 P. lilljeborgi (antea p. 96), I referred to the little tarn below the Y Garn precipices 

 as Llyn y Cwm instead of Llyn cwm Clyd. Llyn y Cwm, the small peaty pool 

 in the saddle between Y Garn and Glyder Fawr, is apparently devoid of mollusca, 

 for I have searched it on several occasions without success. — Chas. Oldham. 

 {Read before the Society, February 14th, 1917). 



