40 
Sedimentary Formations 
Mr. Barkas says there is no description of Urosthenes. This 
is, however, given by Prof. J. D. Dana, in the “ Geology of the 
U. S. Exploring Expedition 1838-1842, under the Command of 
Captain Wilkes , TT.S.JY." (New York), p. 081. His chief ground 
of inquiry is respecting the teeth of these fishes, as he considers 
the Lcpidosteida? are distinguished by the teeth being “ tipped;” 
and, unfortunately, as in many instances in Europe, the New 
South Wales fishes alluded to show no teeth whatever. But, as 
stated in the last edition of this memoir, p. 39, “ the last specimen 
of fish from the PalsDoniscus beds, reported by me to Sir Philip 
Egerton, was a portion of a jaw of a fish whose teeth were of a 
Saurichthyan type, but the learned Icthyologist considered it also 
to be Permian.” The teeth in this specimen were so completely 
“ tipped” in the way mentioned, that I considered it to be a 
Saurichthgs (see Agassiz, “ Poissons Eossilesf vol. ii, tab. 55a.), 
and named it as such, under correction, to Sir Philip. 
The objection of Mr. Barkas may therefore be considered as 
answered ; although the fish to which the jaw belonged is not 
precisely known, Mr. B. says, u from the writings of Professors 
Owen and Agassiz, I learn that Sauricthys is also tipped with 
enamel,” (op. cit.., p. 205). As he admits, moreover, that of the 
eighteen genera Lepidostean which he cites, ten are “ tipped,” it 
is probable that the Ganoid fishes discovered by me, were also 
“ tipped,” though no teeth have been found. 1 was not present 
at the reading of the paper by Mr. Barkas, and did not read it 
in print till 9th February, 1878, or 1 would have replied at the 
time. 
The peculiarity of the teeth in Permian Ganoids was long am> 
pointed out by Dr. King (See 11 Monograph of the Permian Fossils 
of England Palccont. Soc 1850, p. 228, under Platgsomus 
macrurus , p. xxvi, 1.) 
Then, as to the “ vulgar error ” that heterocereal ganoid fishes 
are confined to Palaeozoic beds,— which any one acquainted with 
ordinary treatises on the subject may be supposed to understand 
is an error, though scarcely “ vulgar ” in the ordinary sense 
of that often offensively used term, — surely it may be permitted 
to conclude from the fact that among all the fishes discovered in 
our Coal-beds, and in the beds above the Coal, not a single homo- 
cercal tail has been found, the probability is, as Sir P. Egerton 
has surmised after examination of those submitted to him, that 
the fishes are Palceozoic , especially as the admission is made that 
“ the homocercal structure is not known in Palaeozoic rocks.” 
( u Peport on Coal Fields .” Victoria, 1872, p. G.) 
The fact that the Coal-beds overlie or interpolate the Marine 
beds in what is called “ conformable order,” ought to be con¬ 
sidered a satisfactory conclusion that no break such as ought to 
exist under other circumstances does exist, because whether the 
