34 



THE GEOLOGIST. 



as nowadays the Vicugna prefers the mountains, while its larger congener the 

 Guanaco roams over the Patagonian plains. 



Lastly it was remarked that, as Macrauchenia was an animal combining, to 

 a much more marked degree than any other known recent or fossil mammal, 

 the peculiarities of certain artiodactyles and perissodactyles, and yet was cer- 

 tainly but of post-pleistocene age, it presents a striking exception to the com- 

 monly asserted doctrine that " more generalized" organisms were confined to 

 the ancient periods of the earth's history. For similar reasons the structure of 

 the Macrauchenia is inimical to the idea that an extinct animal can always be 

 reconstructed from a single tooth or a single bone. 



" On the Palaeozoic Fossils brought by Mr. D. Forbes from Bolivia." By 

 J. W. Salter, Esq, F.G.S. 



The fossils of Carboniferous age brought home by Mr. Forbes are the well- 

 known species described by D'Qrbigny. Several are identical with European 

 forms (as Productus Martini, &c), and are cosmopolitan; others are peculiar 

 to the district {Spirifer Condor, Orthis Andii, &c.). 



Mr. Forbes has brought a "Devonian" trilobite (Phacops latifrons or Ph. 

 bufo), in a rolled pebble, from Oruro : it is a widely-spread species. Another 

 allied form was found by Mr. Pantland, many years back, at Aygatchi. In 

 other respects the " Devonian" evidence is scanty. 



In Mr. Forbes' fine collection of Silurian fossils none of D'Orbigny's ten 

 Silurian species occur ; nearly all are such as are met with in Lower Devonian 

 and in Upper Silurian rocks — Tentaculites, Orthis, Ctenodonta, Pileopsis (?) 

 Strophomena, Bellerophon. South Africa and the Falkland Isles yield a similar 

 fossil fauna. The Bilobites in this collection differ, some ' of them probably 

 generically, from D'Orbigny's figured species. A little Beyrichia from the 

 upper part of the Silurian series in Bolivia appears to be like a North Ameri- 

 can form figured by Emmons as Silurian. 



December 5, 1860. 



" On the Structure of the North-west Highlands, and the Relations of the 

 Gneiss, Red Sandstone, and Quartzite of Sutherland and Boss-shire." By 

 Professor James Nicol, F.G.S. 



Geologists' Association. — This Society re-assembled for the winter Session 

 on the 5th November, at 5, Cavendish Square, when the Rev. Walter Mitchell 

 gave a lecture "On the Application of Crystalography to Mineralogy and 

 Geology." 



Crystalography, it was stated, was capable not merely of explaining many 

 facts connected with mineralogy, but also of throwing light on various phe- 

 nomena belonging to geology. Thus, with respect to the latter science, the 

 cleavage of crystals illustrated the great cleavage planes of the stratified meta- 

 morphic rocks, and their modified form assisted in determining the temperature 

 at which strata had been produced. The views and researches of Mr. Clifton 

 Sorby were dwelt upon, and the geometrical laws of Crystalography treated at 

 some length 



Dec. 3. 1860. 



Mr. Mitcliener reaa a paper on a New Red Sandstone quarry at Stourton, in 

 Cheshire. This quarry is remarkable for the abundance of reptilian footprints 

 which it contains. 



Mr. Pickering presented to the Association a very fine collection of land- and 

 fresh -water fossil shells from the Upper Tertiary deposits at Copford, in Essex, 

 aeeonipanvning his observations by an interesting paper descriptive of the 

 loealiiies where they were obtained; and referring also to other brickfields and 

 deposits at Fishcrton, West Hackney. Reculvers, and Ivennet Valley. 



