435 



destroying both sensibility and the power of voluntary motion, par- 

 ticularly as exemplified in the hybernation of animals, to its mecha- 

 nical operation of diminishing the fluidity, or producing solidity, in 

 the oily medium by which these powers are exercised. 



2. A letter from Prof. Hanson to G. B. Airy, Esq., F.R.S., A.R., 



was also read, " On a New Method of computing the Perturbations 

 of the Planets whose eccentricities and inclinations are not small." 

 Communicated by G. B. Airy, Esq., F.R.S. 



The author announces that he has found a method by which the 

 absolute perturbations of planets for any given time, with any given 

 eccentricity and inclination of the orbit, may be calculated ; and he 

 exemplifies his method by applying it to the computation of the per- 

 turbations produced by Saturn on the comet of Encke, in every point 

 of its orbit; a problem of which hitherto there existed no solution. 



3. A paper was also in part read, entitled " On the minute struc- 

 ture of the Skeletons or hard parts of the Invertebrata." By W. B, 

 Carpenter, M.D. Communicated by the President. 



January 19, 1843. 

 GEORGE RENNIE, Esq., V.P., in the Chair. 



John Gould, Esq., Sir Benjamin Heywood, Bart., and Edward 

 Solly, jun., Esq., were balloted for and duly elected Fellows of the 

 Society. 



Captain Edward Belcher, R.N., was balloted for, but not elected 

 a Fellow of the Society. 



The following papers were read : — 



1. " Variation de la Declinaison et Intensite Horizontale ob- 

 servees a Milan pendant vingt-quatre lieures consecutives le 25 et 

 26 Novembre, et le 21 et 22 Decembre 1842." Par Prof. Carlini, 

 For. Mem. R.S. 



2. The reading of a paper, entitled On the minute structure 

 of the Skeletons or hard parts of Invertebrata," by W. B. Carpenter, 

 M.D., was resumed and concluded. 



The present memoir is the first of a series which the author 

 intends to communicate to the Society, and relates only to the Mol- 

 lusca ; and he proposes, hereafter, to extend his inquiries to the 

 skeletons of the Echinodermata, and the various classes of articu- 

 lated animals. After adverting to the classifications of shells pro- 

 posed by Mr. Hatchett and Mr. Gray, from the propriety of which 

 he finds reason to dissent, he proceeds to state the results of his 

 microscopic examination of the texture of shells under the several 

 following heads. First, shells having a prismatic cellular structure, 



