﻿240 Correspondence — Dr. JR.. S. Traquair. 



marginal) portions of certain of the Permian sub-divisions owing 

 to the minor oscillations, resulting in partial failures of deposition 

 and paltry denudations, to which all shallow-water deposits of 

 limited thickness are liable. These were, however, probably mostly 

 inter- rather than post-Permian. Such, for instance, are the cases 

 mentioned in the Survey Memoirs, near Mansfield and Tadcaster, 

 where Middle Permian Marls rest on an eroded surface of the Lower 

 Magnesian Limestone, which at the former place is full of false 

 bedding, and at both exhibits signs of having been sufficiently close 

 to the surface to have locally curtailed or even entirely excluded the 

 deposition of the Middle Marls. I would insist on the importance 

 of discriminating between what is the result of contemporaneous 

 influences (great and small), and what of subsequent causes, in 

 limiting the extension of the Permian formations. If we consent to 

 exclude all evidence that is not provably post-Permian, I think we 

 have yet to learn the grounds for considering that there was in the 

 above district any *' considerable break" between the Permian and 

 the Bunter. 



It is with no small gratification that -I find so eminent a Govern- 

 ment Surveyor as Mr. Aveline is willing to admit that the great 

 break in this district is, as I have laboured in my paper to show, at 

 the bottom and not at the top of the Permians, and that he has 

 become converted to the opinion that the " Lower Eed Sandstone " 

 is a myth. E. Wilson. 



Nottingham, Ibth April, 1877. 



MONOGRAPH ON BEITISH CARBONIFEROUS GANOIDS. 



Sir, — Will you kindly permit me, through the medium of your 

 Journal, to correct and apologize for a very awkward blunder, which 

 occurs in the first part of my monograph on British Carboniferous 

 Ganoids, recently published by the Paleeontographical Society ? In 

 the Introduction I have advocated the retention of the Dipnoi as a 

 distinct order of fishes ; but at p. 41, in a manner unaccountable to 

 myself, for I certainly did not mean it, I have included them as a 

 suborder of the Ganoidei. That this "slip of the pen" was not 

 detected in the revision of the proofs must have been due to an 

 amount of carelessness, of which I am justly ashamed. 



_^prii 2. K. H. Tkaquaik. 



Carbonifeeous Ganoid Fishes. — Errata. 



Page 7, \iae 24:, delete "vfliich." 



„ 12 „ 11,/or "Egerton" reff(f " Agassiz." 



„ 14 „ 3, /or "interclavicular" r««fi? "infraclavicular." 



„ 16 „ 2S, insert a "{" before " Ulonichthi/s." 



,, 28 „ Si, for "or" read ^^ on." 



„ 38 „ 31, /or "centre" »•««!«? "centra." 



„ 41 ,, 34, delete " Suborder I. Dipnoi." 



„ 41 „ 35, /or "II." reas? " Suborder I." 



„ 41 „ 36, ybr "III." 7W(^" II." 



„ 42 „ 4, /or "IV." rea<?" III." 



„ 42 „ 5, for "Y." read'' lY." 



