358

THE FOSSILIFEROUS DEPOSITS

half-filled a single shelfi Now, however, our old obstinateGrauwackes are yielding their organisms,—Dumfries, Gal-loway, and Peebleshire their graptolites, and Girvan and itsneighbourhood its trilobites and its shells. The shores of theSolway near Kirkcudbright are furnishing, though still in-adequately, their fossils of the Upper Silurian ; and it seemsnot improbable that the Girvan locality may be yet found tofurnish characteristic specimens of all the various deposits ofthe Lower Silurian, from those emphatically ancient beds be-neath which only a single organism has yet been detected, upto those superior deposits of the Lower division in which theDudley Trilobite (Calymene Blvmenbachvt) occurs, and whichSir ^Roderick Murchison regards as occupying the same, ornearly the same, horizon as the Upper Caradoc. I am in-formed by our accomplished brother member, Professor Wy-ville Thomson, that in a recent visit to Girvan, he found, inan ancient Conglomerate to the south of the town, specimensof a small lingula and olenus, identical, so far as he couldjudge from their state of keeping, with the fossils of un-questionably the same genera which mark, in the sister king-dom, the primeval zone of life. It would be interesting tofind in our own country, as has already been found in North America , England, and Scandinavia , a base line,—representa-tive apparently of the earliest age of organized being,—fromwhence to commence the geologic history of what our fathersused to term, without quite knowing all that was implied inthe epithet, old Scotland . But whether this base line of theoldest fossiliferous system be found in our country or no, thesystem itself, especially as developed within the southern andwestern districts, must be held to possess a peculiar interest,from the circumstance that, though some of its more curiousfossils have not yet been found in the amply developed andwell-sought Silurians of England, they occur in those of Bo­ hemia on the one hand, and of Canada West and the United