144 

 UP BUCKDEN PIKE WITH THE ANEROID. 



WM. DENISON ROEBUCK, F.L.S. 



Not very much, if any, direct observation of the altitudes to which 

 mollusca ascend the Yorkshire hills appears to have been made ; so 

 that a transcript of the notes made during an ascent of the Wharfe- 

 dale face of Buckden Pike by Mr. W. Eagle Clarke and myself on 

 the 29th of May, 1886, may be of use as a direct record of observed 

 facts. We started from the inn at Buckden (about 700 ft. alt.) and 

 took the road which goes obliquely northwards through Rakes 

 Wood, a scanty coppice clothing the lower slopes of the mountain. 

 Under the plentiful blocks of scar limestone, up to 900 ft. in height, 

 we found Avion ater, Limax agrestis, and Arion bourguignati. 

 We also detected Zonites cellarius (fine), Vitrina pellucida, Zua 

 lubrica, and Clansilia mgosa. At 1,000 ft. we found Arion ater, 

 at 1,030 ft. plenty of typical Limax agrestis, and one at 1,080 ft. 

 At 1,100 ft. a light-coloured example of Arion bourguignati, and 

 on the scars of limestone which line the footpath at 1,150 ft. we 

 found Helix hispida, Pupa U7iibiiicata, and Helix rupestris. Just 

 above Rakes Wood the mountain pasture is reached through a gate 

 at 1,200 ft. Here we found Balea perversa, Helix rupestris, and 

 H hispida, a single Arion bourguignati, and numerous typical Limax 

 agrestis. One small specimen of the latter, a single dead Zonites 

 cellarius, and plenty of Helix rupestris, with H. hispida and Pupa 

 umbilicaia, were found on scars of limestone at 1,280 ft. A range of 

 scars at 1,450 ft. produced numerous Clansilia dubia and Helix 

 hispida, and another, at 1,800 ft, the highest on that side of the Pike, 

 produced a dead Zonites cellarius, Pupa umbilicata, and numerous 

 Helix rupestris, and a few darkish examples of Limax arborum (type). 

 At 1,850 ft. several L. agrestis occurred under stones in the corner of 

 an enclosure, and at 2,010 ft. we found our last mollusc, Arion ater, 

 crawling on the coarse grass. A short time later the summit of the 

 Pike, 2,302 ft. in height, was reached, when the aneroid, on being con- 

 sulted, registered to within a very few feet of the true height. Time 

 did not permit of our working down the Wensleydale slope of the 

 Pike until we reached a steep precipice overhanging the head of 

 Coverdale, where, at about 1,500 ft., we collected a couple of speci- 

 mens of Helix arbustorum var. alpestris, several each of Clansilia 

 rugosa, CI. dubia, and Helix rupestris, and one each of Helix hispida 

 and Zonites cryslallinus, and noticed numerous Limax agrestis and 

 Arion bourguignati. These observations are only scanty, and it is 

 much to be wished that numerous others should be made of the same 

 character, so that we may learn the actual vertical range of the mollusca. 



Naturalist, 



