16 Proceedings of the Royal Physical Society. 



St Lawrence basin, and Orthocemta bearing large siphimcles 

 like those of E'orth America, Scandinavia, and Eussia, should 

 occur in Scotland, and yet be scarcely known further south, 

 is at least suggestive of a geographical distribution — perhaps 

 even of climatical conditions — not very unlike that of more 

 modern times." * 



It is time we now returned to a consideration of the con- 

 tents of our more familiar beds of the south. It will be re- 

 membered that up to about 1849 the only fossil of any im- 

 portance found in the Pentland Hills was an Orthoceras. 

 This appears to have remained the sole representative till the 

 discovery of another shell, Bhynchonella, by Mr A. Geikie 

 (now Director-General of the Geological Survey), in 185 8. -f* 

 In the meantime specimens of this Orthoceras having found 

 their way into Mr Salter's hands, probably through Sir 

 Eoderick Murchison, it was named, in honour of its distin- 

 guished discoverer, Orthoceras Maclareni. \ 



In 1859, the systematic collection of fossils from the 

 Pentland Hills, on behalf of the Geological Survey, was com- 

 menced by the late Mr Eichard Gibbs, whilst the Edinburgh 

 district was in course of being mapped by Messrs Howell 

 and Geikie. § Although a sufficient suit of organic remains 

 w^ere obtained to show the general relation of the beds to 

 the corresponding series elsewhere, the collection made by 

 Gibbs was far from exhaustive, and he left what may be 

 looked upon as virtually a new field for future explorers of 

 fossils. During the Survey examination only two localities 

 were noted as fossiliferous, viz.. Hare Hill and the beds of the 

 North Esk reservoir. From the former two kinds of shells 

 only were obtained, the Bhynchonella compressa, and a Pteropod 

 called Theca. In all twenty-six species of shells were col- 

 lected, viz., Brachiopoda, Bivalves, and Univalves, seven species 

 each. Cephalopoda, three species, and Pteropoda, two species. 



The Brachiopoda do not call for any particular remark, but 



* Quart. Jour. Geol. Soc, xv., p. 381. 

 t Mem. Geol. Survey, ScotL, No. 32, pp. 5, 6. 

 X Siluria, 3d edit., 1859, p. 176, foss. 24. 



§ "Geology of the Neighbourhood of Edinburgh" (Mem. No. 32, 1861. 

 8vo, with Appendix, by J. W. Salter). 



