720 ME. J. E. HAEE AXD DE. H. A. NTCHOLSON 



ceming the importance of the Graptolitoidea as a means of advancing 

 the comparative study of the stratified deposits, and we sometimes 

 feel that Dr. William Smith's dictum as to strata identified by their 

 organized fossils is little heeded in Britain, so far, at any rate, as 

 the Lower Palaeozoic rocks are concerned. If we have added a 

 grain to the weight of evidence that has been accumulating in 

 ecent years, as to the widespread uniformity of fossil-zones among 

 these rocks, we have not laboured in vain. 



§ YII. Desceiptio:!^ op Fossils, 



The Graptolitic fauna of the Stockdale Shales is one which is suf- 

 ficiently well known by the researches of Prof. Lapworth ; and we 

 have not added any new forms during our recent researches. 



The other fossils are chiefly Trilobites, though a few Corals and 

 Brachiopods also occur. 



We append notes upon the new forms and those which have not 

 hitherto been described from British deposits. The Trilobites are 

 difficult to obtain in a good state of preservation, and it would pro- 

 bably require many years' patient collecting to obtain perfect speci- 

 mens of all the forms. Under these circumstances we have refrained 

 at present from minute descriptions, and have drawn up brief 

 diagnoses, which will, we believe, be sufficient to enable others 

 readily to recognize those forms which it was necessary for us to 

 notice on account of their importance as indices to the various non- 

 Graptolitic zones. 



The Coral-fauna of the Stockdale SecL^ is a very limited one, as 

 regards both the variety of species -represented and the number of 

 individuals. The Upper Skfilgill Beds have yielded an undetermin- 

 able species of Lindstrosmia, and a Monticuliporoid has been found 

 in the acuminatus- zone in Skelgill. With these exceptions the 

 known corals of the Stockdale Series are referable to the genus 

 Favosites, and, mainly if not exclusively, to one species of the same, 

 viz. F. mullochensis, J^ich. and Eth. jun. This species occurs abun- 

 dantly in the Silurian rocks of Ayrshire, at ITuUoch Hill and at 

 Woodland Point ; and it is of not very uncommon occurrence in the 

 zone of Phacops glaber in Skelgill. 



Phacops (proper) elegak's, Boeck & Sars. (PI. XYI. figs. 1, la, 2, 

 3, 3 a, 3 6.) 



Trilohites elliptifrons, Esmark, " Om IS'ogle nye Arter af Trilo- 

 biter," ITag. for ISTaturv. Anden E^kke, Bd. i. p. 269. 



Trilohites elegans, Sars & Boeck, Gsea jS"orvegica, p. 139. 



Pliaco]ps quadrilineata^ Ang. Pal. Suec. p. 12. 



Phacops Stokesii, Meszk. " Mon. Tril. d'Ostsee prov.," im Arch, fur 

 IS^at. Liv- Ehst- und Xurl. ser. 1, Bd. i. p. 530. 



Pliacops latifrons, Eichw. Leth. Ross. vol. i. p. 1428. 



Phacops elegans^ Kjerulf, Yeiviser, p. 20. 



Phacops elegans^ E. Schmidt, Eev. d. ostb. Tril. Mem. Acad. St. 

 Petersb. se'r. 7, Tome xxx. J^o. 1. p. 72. 



Phacops elliptifrons, Tornq. " Undersokn. ofv. Siljans. Tril.," 

 Sver. Geol. Unders. ser. C, no. 66. 



