SIS Cambridge Philosophical Society. 



rii^orous determination of tlie date of such dislocations. A large 

 and very valuable portion of the work is filled with descriptions and 

 plates of organic remains, especially of the brachiopodous and 

 cephalopodous molhisca. Most of the species of these classes were 

 probably inhabitants of the deeper parts of the sea, but there are 

 fossil shells in the mountain limestone, which the author supposes 

 to have lived near the shore, and belonging to genera formerly re- 

 garded as foreign to the carboniferous limestone, such as Isocardia, 

 Nucula, Pecten, Patella, Turritelia, and Buccinum. Many species 

 of Zoophytes and Crinoidea are also described and figured in this 

 excellent monograph. 



CAMBRIDGE PHILOSOPHICAL SOCIETY. 



Feb. 13. — A meeting of the Cambridge Philosophical Society 

 was held on Monday evening. Dr. Clark, the president, in the chair. 

 Read — memoir, &c., by Prof. Rigaud of Oxford, on the proportion 

 of land and water on the surface of the terraqueous globe -j memoir 

 by Prof. Challis, on the law of decrease of temperature in ascend- 

 ing in the atmosphere; memoir by Mr. Kelland, on the transmission 

 of light through crystallized media. 



Feb. 27. — A meeting of this Society was held on Monday eve- 

 ning, the president, Dr. Clark, being in the chair. A paper by Mr. 

 Warren, of Jesus College, was read, on the algebraical sign of the 

 perpendicular, drawn from a given point to a given straight line. — 

 Mr. C. Darwin exhibited various specimens of rocks, collected by 

 him in a voyage round the world, made in His Majesty's ship 

 Beagle, Capt. Fitzroy, and occupying five years. These specimens 

 were — tubes of fused sand (produced by lightning?) found near 

 the Rio Plata ; a white calcareous incrustation alternately formed 

 and removed on the rocks of Ascension Island by a periodical change 

 in the direction of the swell ; a black incrustation formed by the 

 spray on the tidal rocks at Ascension ; a white hard calcareous 

 rock formed rapidly at Ascension ; a recent calcareous formation 

 indurated by the contact of lava at St. Jago, one of the Cape de 

 Verde islands. — Afterwards Mr. W. W. Fisher gave an account of a 

 case of Spina Bifida, accompanied by some physiological and pa- 

 thological researches on the accumulation of fluid in the ventricles 

 of the brain. He came, from the facts he brought forward, to the 

 following conclusions : — That as there exists a correspondence be- 

 tween the development of the central part of the nervous system 

 and the organs destined to protect it, (the development of the os- 

 seous portion being subordinate to that of the nervous, by reason 

 perhaps of its subsequent formation,) so the organic characters of 

 the parts contained, and the peculiar construction of the parts con- 

 taining, require that a reciprocity of adaptation should afterwards 

 exist between them ; — That the pia mater, except where it is united 

 with the arachnoid so as to present the generic character of a serous 

 membrane, possesses a faculty of secreting a fluid, the quantity of 

 which is limited by the degree of resistance offered by the inclosing 

 parts, und that it is thereby calculated, by its particular arrange- 



