386 



THE GEOLOGIST. 



rocks. The discovery is all the more important that so few of the class have 

 been found in any of the numerous localities of the Old Red — one or two in 

 England, more abundantly in Russia, and even there of comparatively rare 

 occurrence. " f One shell, however, the Atrypa reticularis" says the author of 

 Siluria, " ranges even to the furthest known geographical limits of the Devo- 

 nian rocks ; to Armenia, the Caucasus, and China on the east, and to the 

 Devonian deposits of America on the west.*" 



I forwarded a small slab of the deposit to Mr. Salter, who has returned for 

 answer, as the result of his examination, " Though very obscure, there cannot 

 be much doubt of the bivalve shell being a Modiola or related genus ; but it is 

 so imperfect that I should not like to say whether this very thin shell is a 

 marine one or not. The same with the Entomostraca. They may be Cypris, 



but are quite as likely Cy there I may further mention that a shell somewhat 



like is found in the Lower Old Red of Shropshire, accompanied by marine 

 genera of Entomostraca. The species is probably new." This interesting 

 fossiliferous slab is now placed in J ermyn-street Museum. 



There are, in addition to the above, several other forms of mollusca, one of 

 which resembles the genus Atrypa, another is like the typical Spirifer, and 

 some are so thin and broken as scarcely to present their true characteristics. 

 They are, however, sufficiently numerous, and to be easily extracted from their 

 soft marly matrix. Better specimens are therefore to be looked for, and probably 

 also various new genera in a deposit otherwise so rich in organic forms of 

 marine life. Some of the shells are smooth, and others deeply and beautifully 

 striated. Some are so extremely filmy as to be almost detached by the breath, 

 or break by a slight impression of the nail. 



The Entomostraca are exceedingly numerous, some microscopically 

 minute, and others large enough to be examined by the naked eye. A bed of 

 fully an inch thick is entirely composed of myriads of these organisms, fresh 

 in colour, and perfect in outline and structure as when they sported in the 

 waters and shallows of the Devonian seas. The mass is extremely friable and 

 brittle, as consisting chiefly of these minute bodies themselves, and a soft cal- 

 careous or aluminous matrix of a light bluish colour. Organisms of the same 

 family are distributed up and down in the thirty feet of exposed rock, as if 

 floating everywhere in the turbid water, they had dropped at random into the 

 muddy silts. The richer portion is towards the base of the cliff, and consists 

 almost exclusively of the creatures bodies themselves, agglutinated by a thin 

 paste of calcareous shale. 



I shall now conclude with a few general remarks, as serving to show the 

 relations and theoretic value of this new fossil locality, and the bearings more 

 especially upon our Scottish palaeontology, some recent northern conclusions of 

 which may be thereby disturbed. 



1. Do these grey flagstones and indurated shales form part of the Devonian 

 system, or true Scottish Old Red sandstone ? I have in my own mind not the 

 slightest doubt about the answer that must be given to'the question. The 

 other members of the series are all in the immediate vicinity ; and from Park- 

 hill to Gleneagles — thirty miles in linear distance along the slope of the Ochil 

 range — the grey and blue coloured tilestones can be distinctly traced through- 

 out, feat hering out and in among the traps and in various places exhibiting the 

 s;i me I oxl urc and marly character as the Dron deposit. At the same time it 

 has to be stated that some regard this as the wider Carboniferous series. Mr. 

 Powric, upon a short inspection, all but concluded that it was ; and in corro- 

 boration of these views, I have to mention that pits in search of coal have been 



Siluria, 3rd edition, p. 297. 



