Linncean Society. — Geological Society. 229 



were proposed. A paper was read, entitled " Observations on the 

 Trachea£ of Birds, with descriptions and representations of several 

 not hitherto figured : by William Yarrell, Esq. F.L.S." — The ex- 

 traordinary structures described by the author, are that of the 

 crested Pintado of Africa (Numida cristata, Pall.), the Demoiselle, 

 the Stanley Crane, the Black Swan of New Holland, and other 

 swans, geese, and ducks. It was remarked that all birds with a com- 

 plex structure of trachea have loud harsh voices, while the simple 

 forms belong to the delightful song-birds. The paper concluded 

 with an arrangement of the British species of the Duck family. 



Feb. 20. — A Description, by Bracy Clark, Esq. F.L.S. of a new 

 species of Bot from the Illinois, was read. Also a continuation of 

 Mr. W. S. MacLeay's paper on the Comparative Anatomy of cer- 

 tain birds of Cuba. 



GEOLOGICAL SOCIETY. 



Feb. 2. — The reading of a paper was concluded, " On the coal- 

 field of Brora in Sutherlandshire, and some other stratified deposits in 

 the north of Scotland ;" by R. I.Murchison, Esq. Sec, G.S. F.R.S. 



The Brora coal-field forms a part of the deposits, which on the 

 S.E. coast of Sutherlandshire occupy a tract of about twenty miles 

 in length, from Golspie to the Ord of Caithness; and three miles in 

 its greatest breadth ; — divided into the valleys of Brora, Loth, and 

 Navidale, by the successive advance to the coast of portions of the 

 adjoining mountain range which bounds them on the W. and N.W. 

 Thetirst of these valleys is flanked on the S.W. by hills of red con- 

 glomerate ; which pass inland on the N.E. of Loch Brora, and give 

 place to an unstratified granitic rock that forms the remainder, 

 of the mountainous boundary. 



With a view to the comparison of the strata at Brora with those 

 of England, the author had previously examined the N.E, coast of 

 Yorkshire, from Filey-Bridge to Whitby, comprising the coal-field 

 of the Eastern Moorlands above the lias. 



The highest beds at Brora consist of a white quartzose sandstone, 

 partially overlaid by a fissile limestone, containing many fossils, — 

 the greater number of which have been identified with those of the 

 calcareous grit beneath the coral rag ; — and along with these Mr. 

 Sowerby has discovered several new species. The next beds, in a 

 descending order,are obscured, in the interior, by the diluvium which 

 is generally spread over the surface of these valleys, but are ex- 

 posed on other places on the coast ; and they consist of shale with 

 the fossils of the Oxford clay, overlying a limestone resembling 

 cornbrash and forest-marble, the latter associated with calciferous 

 grit. To these succeed other sandstones, and shales containing 

 belemnites and ammonites, through which the shaft of the present 

 coal-pit is sunk, to the depth of near 80 yards below the level of the 

 river Brora. The principal bed of coal is 3 feet 5 inches in thick- 

 ness, and the roof is a sandy calcareous mixture of fossil shells, and 

 a compressed assemblage of leaves and stems of plants, j)assing into 

 the coal itself. The fossils of this and the superior beds are identi- 

 cal for the greater part, with those which occur in the strata above 



the 



