654 
of a series of specimens from this bed at Axmouth and Aust, M. Agas- 
siz determined four species to be well-known forms of the Muschel- 
kalk, whilst fifteen were unknown in-that deposit or any other part 
of the triassic group; and Sir Philip concludes, that the beds in 
question ought to be removed from the lias, not only because the 
fishes are specifically distinct from those of that formation, but be- 
cause the forms of the ganoidians possess the heterocerque tail, a 
form which the classification of Agassiz confines to deposits of 
higher antiquity. This reason ought to have great weight, and 
might, if unconnected with others, at once dispose us to move our 
base line of the lias some few feet higher. 
_ A fresh-eut section of the Gloucester railway had exposed at Combe 
Hill, near Cheltenham, the same singular bone-bed which is so well 
known at Axmouth and at Aust. From an intimate knowledge of 
that country, I can recognize the fidelity with which Mr. Strickland 
identifies certain thin layers of sandstone and prit at the bottom of the 
lias extending to the north with the adjacent bone-bed, which in its 
further extension loses those ichthyolite characters for which it is so 
remarkable over an area in our isles as wide, indeed, as that of the 
famous “ Ktipfer Schiefer” inGermany. Now in Gloucestershire the 
bone-bed described by Mr. Strickland contains not only fishes, many 
of which are of new species, but also many sheils, some of which are 
supposed to be of forms intermediate between those known in the lias 
and the keuper. In this case, therefore, we are probably in the same 
position as the inquirer into the Paleozoic rocks, who stands upon 
the beds of passage from the Silurian into the Old Red or Devonian 
rocks before adverted to. In both eases, when he finds forms which 
- belong to the inferior and superior systems, whether he may draw 
his boundary line above or below these equivocal strata, seems at 
first to be of small importance ; for, as with the progress of research, 
we must expect to find an infinite number of strata which contain 
fossils indicating a transition from lower to higher formations, so 
must the lines of separation which geologists set up between forma 
tions be liable to undergo small alterations. Adhering, however, to 
the belief, that in the sequel those limits will most prevail which are 
most made to depend on great changes in animal economy, I think 
that the conclusion of Sir Philip Egerton, as based en the existence 
of the fishes with heterocerque tails, must lead us to place the “ bone- 
bed” as the uppermost limit of our New Red System, or in other 
words, as the last-formed stratum in which such ichthyolites appear. 
A point connected with an important previous deduction has been 
determined by Mr. Strickland in a cutting of the Gloucester rail+ 
road. The period at which the Lickey trap rocks were erupted, 
is now proved by actual sections to be that which from colla- 
teral circumstances had been surmised by myself. By observing 
that the New Red Sandstone of the Upper Lickey lies unconform- 
ably upon a mass of Red Sandstone, Mr. Strickland has demon- 
strated that the disturbance and elevation of the ridge took place 
after the deposit of the Lower New Red Sandstone, and anterior to 
the accumulation of the New Red, properly so called. In this fact 
