Rev. A. Irving — Reply to Prof. Hull. 559 



as well as Greenland and the Eastern and Western coasts of North 

 America (Jeffreys, op. cit. vol. iv. p, 321). 



XII. Fnsus Fahricii. — Jeffreys only gives Greenland and tlie 

 White Sea as the habitat of this shell (op. cit. vol. iv. p. 322). 



XIII. Littorina exjyansa. — This is apparently the Turho expansus 

 of other writers, and the only habitat I can find for it is that given 

 by Forbes as Arctic Seas, and coasts of America. 



XIV. Margarita inflata. — The Turho inflatus and Turho Groenlayi' 

 dtcus of other writers. It lives, says Jeffreys, in every part of the 

 Arctic Ocean, and on the coasts of the White Sea, Scandinavia, 

 Iceland, Canada, and the States of Maine and Massachusetts, and he 

 mentions also its occurrence as local, but not uncommon, about tlie 

 West of Scotland, the Orkneys and Shetlands, in Dannet Bay, 

 Caithness, etc. (op. cit. vol. iii. p. 299). 



XV. Velutina undata. — This shell occurs in the seas of Boreal 

 America (Forbes, p. 422). 



XVL Natica clausa. — This shell occurs in Scandinavia as far 

 south as the Christianiafiord ' (Jeffreys, vol. iv. p. 229). 



This examination is assuredly very impressive. Of the various 

 shells enumerated by Forbes and others as proving glacial conditions 

 to have surrounded them when alive, there is hardly one which is 

 not still living in the North Atlantic at the present moment under 

 conditions completely different to those we desoi'ibe as glacial. No 

 doubt these shells do live and thrive in very high latitudes, and 

 doubtless also have their focus there at this moment ; but it is no less 

 true that they extend down into the temperate regions of our own 

 seas and those of the United States and of Southern Scandinavia. If 

 the whole of the mollusca of the beds we ai-e dealing with belonged 

 to the same facies, we should be bound no doubt to conclude that 

 the conditions of South Greenland or of Iceland prevailed here when 

 these shells were living ; but the fact is this class forms a small 

 proportion of the whole. Here we must at once say that Forbes's 

 method of tabulating the results of his examination of all the beds 

 together will no longer be deemed satisfactory. We have now 

 the clearest evidence both in Scandinavia and in Britain that some 

 of the beds have a much more arctic facies than others. We have 

 in both areas beds which apparently represent the old sea-bottom 

 of mud or sand with the shells still remaining in situ, bivalves 

 standing erect with both valves intact, and with all the appearance 

 of being undisturbed. These are the lower beds. For the most 

 part, so far as I know, they occur at low levels and are characterized 

 largely by shells of an arctic type. 



{To be continued.) 



VII. — The Permian and Tkias — Eejoinder to Prof. Hull. 



By Eev. A. Irving, B.A., B.Sc, F.G.S. ; 

 of Wellington College. 



PEOFESSOR HULL'S criticisms (pp. 491-5 of this volume) on 

 a former paper of mine on the " Classification of the Permian 

 and Trias " lay upon me the burden of a brief reply. I may say 

 1 Dr. Van Geuns discovered it in a Pliocene bed near Palermo. 



