240 
Correspondence — Dr. R. H. 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 wliicli all shallow-water deposits of 
limited thickness are liable. These were, however, probably mostly 
iuter- ratker 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, wkich 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 Red Sandstone ” 
is a myth. E. Wilson. 
Nottingham, löt/t April, 1877. 
MONOGRAPH ON BRITISH CARBONIFEROUS GANOIDS. 
Sir, — W ill 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 publisked by the Palaeontograpliical 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 askamed. 
April 2. R. H. Traquair. 
Carboniferous Ganoid Fishes. — Errata. 
Page 7, line 24, delete “which.” 
„ 12 „ 1 1, for “Egerton” read “Agassiz.” 
14 „ 3, for “ interclavicular ” read “ infraclavicular.” 
„ 16 „ 28, insert a “ before “ JElonichthys.” 
,, 28 „ 34, /or “or” ra«7 “ on.” 
„ 38 „ 31, /or “centre” rend “centra.” 
„ 41 „ 34, delete “ Suhovder I. Dipnoi.” 
„ 41 „ 35, for “II.” read u Suborder I.” 
„ 41 ,, 36, /or “ III.” read “ II.” 
„ 42 „ 4,/or “ IV.” read “ III.” 
,, 42 „ 5, for “ V.” read “ IV.” 
