Royal Society. 383 



much thicker and shorter than before. There is a remarkable en- 

 largement of the thoracic nerves, particularly of those sent to the 

 wings; and those belonging to the posterior pair of legs are cu- 

 riously convoluted within the thorax, preparatory to their being un- 

 coiled at the instant of the change being made to the pupa state. 



These changes are followed minutely through several stages of 

 development. The author expects to be able to lay before the So- 

 ciety, in a subsequent paper, the results of his investigation of the 

 remaining stages, and to offer some observations upon the manner 

 in which these changes are effected. 



June 21. — Papers were read, bearing the following titles: 



1. "An Account of the magnetical Experiments made on the 

 Western Coast of Africa in 1830 and 1831," by Commander Edward 

 Belcher of H.M.S. Etna. Communicated by the Rev. George Fisher, 

 M.A. F.R.S., through Captain Beaufort, R.N. F.R.S. 



The object of the inquiry specified in this paper, and of which the 

 results are given in a tabular form, was to determine the relative 

 horizontal intensities of terrestrial magnetism on the different parts 

 of the coast of Africa which the author lias been lately employed in 

 surveying. The experiments were made with four needles con- 

 structed by Dollond on the model of those of Professor Hansteen ; 

 and the permanence of their magnetism during the voyage was veri- 

 fied by a comparison of trials made in England before and since the 

 voyage. Errors arising from local causes of irregularity were 

 guarded against by varying the places of observation at each station, 

 and taking mean results. 



2. " On the Use of a substance called the False Tongue in Foals," 

 by Professor Sewell, of the Royal Veterinary College. Communi- 

 cated by Sir Charles Bell, F.R.S. 



The substance called x\\q false tongue, which is thrown out from 

 the mouth of the foal, cither at the period of birth, or shortly before 

 it, and to which various whimsical uses and virtues have been 

 assigned, is conceived by the author to be requisite in this animal 

 for the action of sucking, in consequence of its not respiring through 

 the mouth, but altogether tlu'ough the nasal passages : an instinc- 

 tive feeling prompting it to supply the loss of that substance by suck- 

 ing the teat of the mother. Dr. Prout, who analysed a portion of 

 this substance at the request of the author, finds it to be composed 

 principally of coagulated albumen .slightly modified. The author 

 regards it as a secretion from the tongue of the foal. 



3. "Journal of the Weather, kept at High Wycombe during the year 

 1831, with monthly Observations," by James G. Tatem, Esq. Com- 

 municated by William Allen, Esq. F.R.S. 



4. " Physical and Geological Observations on the Lake of Oo near 

 Bagneres de la Chou, in the year 1831," by M. Neree Boubce, Pro- 

 fessor of Geology at Paris. Communicated by P. M. Roget, M.D. 

 Sec. R.S. 



The author ascertained that the bottom of the lake, which is 230 

 French feet in depth, forms a level plane of great extent, and is co- 

 vered with a stratum of mud composed of fine micaceous sand of a 



