Geological Society, 399 



dal. Sella, however, relying apparently upon the evidence afforded 

 by the lustre and colour of the scales, for he was unable to obtain 

 any measurements, expresses his conviction that they are not differ- 

 ent from pure boron. Some scales of this substance, for which, as well 

 as a supply of crystals of pure boron, I am indebted to Dr. Matthies- 

 sen, have faces on their edges, but so narrow that the reflected image 

 of the bright signal is diffracted into aline of considerable length, and 

 therefore difficult to bisect. For this reason it is not possible to de- 

 termine the positions of the faces with accuracy. 



One of them, about 2 millims. wide and 0*014 millim. thick, 

 of the shape of half a hexagon divided by a line at right angles to 

 two opposite sides, exhibited faces agreeing in position very fairly, 

 considering the unavoidable errors of observation, with two of the 

 faces k, two of the faces e, c, m, three of the faces b, two of the faces 

 x t q, three of the faces h, and four of the faces a. Another, smaller 

 and thinner, of the shape of a hexagon, had faces coinciding with 

 two of the faces Jc, two of the faces e, c, m, f, v, and four of the faces 

 h. The agreement in position of so many of the faces with those of 

 pure boron appears to leave but little doubt of the identity of the 

 forms of the two substances. 



GEOLOGICAL SOCIETY. 



[Continued from p. 319.] 



February 21, 1866. — Warington W. Smyth, Esq., President, 

 in the Chair. 



The following communications were read : — 



1. " On the Tertiary Mollusca of Jamaica." By R. J. Lechmere 

 Guppy, Esq. 



In 1862 Mr. Lucas Barrett deposited in the British Museum a 

 collection of Miocene fossils from Jamaica ; and the author having 

 described the nature of the beds whence the fossils were obtained, 

 remarked on the extended development of the Miocene formation in 

 the Caribbean area. From his examination of the fossils, he was 

 able to confirm many of the conclusions arrived at by Mr. Carrick 

 Moore from his investigation of the San-Domingo fossils, and by 

 Dr. Duncan's and Prof. Rupert Jones's investigations of the Corals 

 and Foraminifera of the West-Indian Miocene deposits. 



The author considered that the Middle Tertiary beds of San 

 Domingo, Cuba, Cumana, and the Caroni series in Trinidad, toge- 

 ther with the Miocene deposits of Jamaica, represent the upper or 

 later part of the West- Indian Miocene; while the chert formation 

 of Antigua, the Anguilla beds, and the beds exposed at San Fer- 

 nando in Trinidad belong to the lower and older part of the same 

 formation. 



Reference was then made to the distinguishing features and cha- 

 racteristic fossils of the beds exposed in the several localities named ; 

 and in endeavouring to correlate the beds in the different islands, 



