XC PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



careous spar, with the axes of the rhombs perpendicular to the original 

 plates of the shell. Thus, Mr. Mallet considers, a molecular induc- 

 tion of crystalline form appears to have been propagated from the 

 primary nuclei of crystals deposited in the original cavities of the 

 shell, such that all the calcareous particles of the latter took a new 

 arrangement in obedience to the form and position of these primary 

 rhombs. He infers a change without solution, and therefore that the 

 fact observed belongs to a class that might be much extended with 

 valuable results. He remarks that belemnites in calcareous strata 

 always assume the form of arragonite and not of calcareous spar. 



The second paper by Mr. Mallet was on the adoption of an uniform 

 principle of making geological sections. He proposes that all geolo- 

 gical sections should be made in north and south and in east and west 

 directions. He showed by a map of parallel sections of an imaginary 

 country, so laid down on the same sheet at equal distances, that a 

 complete picture of the interior of the country may be produced, 

 and that from such a set of parallel sections, at right angles and 

 equidistant, other sections at any required angle between north and 

 south and east and west may be derived and laid down by well-known 

 mathematical methods. He considers that if this system were 

 adopted it would give uniformity and mathematical precision to all 

 future sections, as from them, without limit, any other sections might 

 be derived. Mr. Mallet remarks, that as our globe has all its great 

 forces in connexion with lines of symmetry on its surface, i. e. north 

 and south or east and west, there is reason to desire that our geolo- 

 gical sections should also be in lines of symmetry, as at some distant 

 time they must connect themselves with the great cosmical forces 

 concerned both ^^ith the apparent unsymmetrical confusion of the 

 surface, and with the real order of forces ever acting within and upon 

 our globe. 



Mr. M'Adam communicated a notice of the cuttings of the Belfast 

 and Ballymene Railway, describing the appearance of the trappean 

 rocks and of the drift cut through. 



The other papers were from officers of the Geological Survey. 

 Professor Oldham, the president of the Geological Society of Dublin, 

 described in detail and exhibited a map of the area covered by drift 

 in the county Wicklow. He also exhibited and described the maps 

 and sections of the same county lately published by the Survey, and 

 Professor Edward Forbes gave a detailed notice of certain fossils, 

 apparently the oldest that we are yet acquainted with, to which he 

 assigned the name of Oldhamia, having been first observed by Pro- 

 fessor Oldham, near Bray, in 1844. Professor E. Forbes also com- 

 municated to the Society an account of the researches of the Survey 

 into the Silurian fossils of Ireland, especially those of Portrane, and 

 Mr. Du Noyer read a paper descriptive of the mode of occurrence of 

 certain interesting dykes, so well exposed by the railway cuttings of 

 the Belfast Junction Raihvay, near Dundalk. 



The Geological Society of Cornwall has contiiuied to advance. 

 Mr. Pattis^on communicated " A brief description of the coast of 

 Cornwall between the Padstow River and Perran Sands," in which 



