136 Reports and Proceedings — 



for a reservoir, was found to be occupied by thick beds of gravel of 

 different character from the valley -gravels, and not of fluviatile or 

 estuarine formation ; the same gravel occurs upon other elevations, 

 and patches of it, appearing here and there, show that it probably 

 once extended right along the ridge and over Hanger Hill. Similar 

 materials to those forming this gravel also occur scattered over the 

 surface of the ground. On the Mount these gravels filled a series 

 of furrows or channels, beneath which were horizontally stratified 

 deposits of white sand, loam, and loamy clay, which were pressed 

 out of the line of deposit where the jagged furrows occurred ; and 

 from all the characters presented the author inferred that these 

 deposits were due to the action of ice which had stranded and melted 

 here, and deposited its burthen of glacial detritus. The author 

 described the deposits of gravels, brick-earth, etc., at various points 

 in the district, and noticed that the high-terrace gravels between 60 

 and 125 feet contain seams of black matter, apparently due to the 

 decay of vegetable substances, which recur at more or less regular 

 intervals, and serve to indicate three or four lines of old land- 

 siu-faces. In connexion with these land-surfaces, especially in some 

 pits excavated in the Creffield Eoad, about 100 feet above 0. D., 

 numerous worked flints were found, the characters and mode of 

 association of which led the author to think that we have here traces 

 of a regular manufactory of flint implements. He further indicated 

 the conditions under which he considered their preservation in this 

 locality had taken place. 



IT.— Feb. 10, 1886.- Prof. T. G. Bonney, D.Sc, LL.D., F.K.S., 



President, in the Chair. — The following communications were read : 



3. "On a new species of Psilotites from the Lanarkshire Coal- 

 field." By R. Kidston, Esq., F.G.S. 



The specimen described, which was found by Mr. Walter Burns 

 in 1884, consists of three parallel branchlets with thorn-like projec- 

 tions on one side only. The author describes these as a form of 

 Goldenberg's genus Psilotites, and points out that they have much 

 resemblance to Dawson's Psilophyton. 



2. " The Melbourn Rock and the Zone of Belemnitella plena, from 

 Cambridge to the Chiltern Hills." By W. Hill, Esq., F.G.S., and 

 A. J. Jukes-Browne, Esq., F.G.S. 



The " Melbourn Rock," which was first defined by one of the 

 authors in 1880, is a band of rocky chalk which forms the base of 

 the Middle Chalk in Cambridgeshire, and occurs about 80 feet above 

 the " Totternhoe Stone." In the present paper it was shown, as the 

 result of the mapping operations of the Geological Survey, to form 

 a well-marked and constant feature in the counties of Hertford, 

 Bedford, Buckingham, and Oxford. In the original description of 

 the Melbourn Rock it was confounded with the "Zone of Belem- 

 nitella plena in a remanie condition," as described by Dr. Barrois ; but 

 it was now pointed out that the latter horizon is distinct from and un- 

 derlies the latter. Although the zone of Belmnitella plena has been 

 very largely removed by erosion in the district described, there is, 



