134 Correspondence — Mr. F. A. Bather. 



the fauna and flora are identical, and both are of Recent age ; 

 a physical connection would necessitate an uplift of the ocean bed 

 to a minimum extent of 550 fathoms. 



As regards the epoch of maximum elevation, I have already given 

 my reasons for holding that the extreme cold of the Glacial Epoch 

 was the direct result of land elevation on both sides of the Atlantic 

 (see my paper on " Another Possible Cause of the Glacial Epoch," 

 Trans. Vict. Inst., 1898) ; under this view, it follows that the 

 intensest cold would probably occur during the epoch of maximum 

 elevation, namely, the early stage of the Glacial Epoch. I need not 

 further dwell on this point, which I have attempted to deal with 

 in the paper referred to. 



But this communication has extended far beyond my original 

 intention, and I must bring it to a close. It seems to me that this 

 correspondence has " cleared the air," and that between the views 

 of Professor Spencer, Mr. Jukes-Browne, and myself there is but 

 little difference ; or the difference is unimportant. 



Edward Hull. 



THE HORIZON OF DINOGYSTIS BARROISI.^ 



Sir, — Professor G. Dewalque, writing in your February number 

 (n.s., Dec. IV, Voh VI, p. 94), gently turns the Eamennian beds of 

 the Condroz right way up again from the reversed position into 

 which an annoying slip on p. 543 of my paper had thrown them. 

 For this friendly intervention he has my thanks, but with his main 

 thesis I am unable to agree. The question at issue is the horizon of 

 Dinocystis Barroisi ; to this all the rest is subsidiary. Let us make 

 the question clear by printing the list of the horizons of the 

 Famennian, in descending order, as given in " Legende de la Carte 

 Geologique de Belgique, etc.," 8vo, Bruxelles, 1896. 



Devonien superieur. 



Famennien superieur. 



Assise de Comblain-au-Pont [=Etroeungt Limestone]. 

 Assise d'Evieux. 

 Assise de Monfort. 

 Assise de Souverain-Pre. 



Famennien inferieur. 



Assise d'Esneux. 



Assise de Mariembourg. 



Assise de Senzeilles. 

 This list does not imply an absolute vertical succession : it appears, 

 for instance, that the Assise d'Evieux, with its rich flora, may be 

 a more littoral facies of the Assise de Monfort, while the Assise 



1 See Geol. Mag., n.s., Dec IV, Vol. V, pp. 543-8 (December, 1898). Footnote 1 

 on p. 647 explained the name Dinocystis as derived from deivSs, terrible. Although. 

 this seemed peculiar, it did not occur to me that Dr. Jaekel must have intended to 

 derive it from ^ivitv, to tvhirl round, in allusion to the marked curvature of the radial 

 grooves. Thus regarded, the name is highly appropriate. 



