lloyal histitution, 533 



order C^csalpinete, and tribe CassiecB. Mr. Bentham adopts the na- 

 tive name for the genus, and proposes that of excelsa for the species. 



The genus is nearly related to Tachigalia of Aublet, and Leptolo- 

 hium of Vogel, but differs from both in the woody texture of the 

 pod, which is moreover naturally dehiscent, in the greater regularity 

 of the parts of the flower, and in the sterility of the alternate sta- 

 mina. 



April 3. — Read a communication on the existence of Stomata 

 in Mosses. In a letter to R. H. Solly, Esq., F.R.S. & L.S. By Wil- 

 liam Valentine, Esq., F.L.S. 



The discovery of stomata in mosses was reserved for Mr. Valen- 

 tine, an opinion of their absence from that family having univer- 

 sally obtained amongst botanists. It was in Bryum crudum that Mr. 

 Valentine first detected stomata, and of one hundred and three Bri- 

 tish mosses examined by him, seventy-eight were found to possess 

 these organs. Their situation in this family is very remarkable, be- 

 ing confined, with one exception, to the theca, and the thinness of 

 the tissue will readily account for their absence from other parts. 



The more common form of the stomata in mosses is similar to that 

 generally found amongst phsenogamous plants. Each consists of two 

 oblong reniform cells, with their concave sides opposed to each other. 

 In Funaria hygrometrica they consist of a single cell in the form of 

 a hollow ring, and in five British species of Orthotrichum (diaphanum, 

 pulchellum, rivulare, anomalum, and cupulatum) they have a raised 

 border of projecting cells which form a cavity above the stoma, re- 

 sembling somewhat those of Marchantia and Targionia. 



ROYAL INSTITUTION. 



April 27. — Mr. Grainger on the physiology of the spinal cord. 



May 4. — Mr. Hickson on vocal music as a branch of education. 



May 11. — Mr. Brayley on the Theory of Volcanos. The subject 

 was introduced by allusion to the important results which have 

 ensued from the recent direction of the minds of mathematicians to 

 the philosophy of geology, and from the application to the theory 

 of geological phsenomena, both of actual mathematical analysis and 

 of general mathematical reasoning. Mr. Hopkins's researches on the 

 mechanical theory of elevation, recently applied by Prof. J. Phillips 

 to exi)lain the structure of parts of the North of England, and the 

 theory of volcanic action dependent on that of the secular varia- 

 tion of the isothermal surfaces within the globe, in which Mr. Bab- 

 bage and Sir John F. W. Herschel have independently concurred, 

 having been cited as examples of those results, the object of the 

 present communication was stated to be, first, the familiar exposition 

 of that theory ; and, secondly, to offer reasons why the chemical 

 theory of volcanos originally proposed by Sir Humphry Davy, should 

 not be discarded ** as a mere chemical dream," even on the high 

 authority of Sir John Herschel. 



The foundation of the former theory being the observed augment- 

 ation of temperature, as we descend from the surface of the earth » 

 towards its interior, a brief statement of the general result of the 

 observations hitherto made on that subject was first given, illustrated 



