256 Rev. P. B. Brodie on the Geology of the 



animal within the shell was blackish brown, the foot livid, and 

 rayed on the upper side with the darker colour. No species of 

 Lymncea occurred to me at the Cape, though I took near Cape 

 Town an Ancylus and several species of Physa distinct from those 

 discovered by Krauss and Wahlberg in the eastern part of the 

 colony. My first specimens of Physa were taken nearly three 

 months after the observation of Succinea. 



In addition to the above circumstances, I may here note that, 

 in 1833, I took Succinea creeping on stones under water in com- 

 pany with Lymncea stagnalis, peregra and auricularia, Planorbis 

 marginatm and vortex, Bithynia impura and Physa fontinalis, in 

 Lough Carrigan, county Cavan, Ireland, which fact 1 entered 

 carefully in my conchological journal. It militates against the 

 opinion of some authors, and indeed against my own observations 

 on the habitation generally selected by the animal of Succinea, 

 which I have had occasion to remark elsewhere in Great Britain, 

 India, Mauritius and Germany. Moreover Succinea crassiuscula, 

 nobis, an inhabitant of the whole of Gangetic India, is so inde- 

 pendent of the presence of standing or running water, that it 

 frequents the walls of ravines and precipitous banks where no 

 water ever lodges, and where it can receive no moisture but that 

 derived from dews or from the fall of the periodical rains. 



Aix la Chapelle, July 30th, 1850. 



XXIII. — Sketch of the Geology of the neighbourhood of Grantham, 

 Lincolnshire; and a comparison of the Stonesfield Slate at 

 Collyweston in Northamptonshire with that in the Cotswold 

 Hills. By the Rev. P. B. Brodie, M.A., F.G.S.* 



The object of the present paper is to give a short account of the 

 geology of a portion of the county of Lincolnshu-e, especially in 

 the neighbourhood of Grantham and Stamford, and to point out 

 its identity in many respects with certain parts of Gloucestershire. 

 The formations observable in the district above mentioned are 

 the Great Oolite, Stonesfield Slate, and Lias. The Great Oolite 

 (and some of the superior overlying groups, including in places 

 the cornbrash) may be traced with considerable regularity from 

 Minchinhampton in this county in a north-easterly direction 

 to Stamford, whence it pursues a more northern course into 

 Yorkshire. The Great Oolite is extensively quarried at Ketton 

 and other places near Stamford, and affords a good building- 

 stone, more or less full of fossils ; one bed, in which I found 



* Read at the Meeting of the Cotswold Naturalists' Club, June 18, 1850, 

 and with slight alterations at the last Meeting of the British Association for 

 the Advancement of Science, August 1850. 



