45 
JNGLEBOROUGH. 
]'ART IV.* STRATIGRAPHY AND PALEONTOLOGY OF THE 
SILURIAN. 
BY T. M^KENNY HUGHES, M.A., F.R.S., F.G.S., WOODWARDIAN 
PROFESSOR OF GEOLOGY IN THE UNIVERSITY OF CAMBRIDGE. 
" Each country ought to be described without any accommo- 
dating hypothesis, according to the type after which it has been 
moulded. But, in comparing the unconnected deposits of remote 
countries, we must act on an opposite principle ; learning to 
suppress all local phenomena, and to seize on those only which 
are coextensive with the objects we attempt to classify." Sedg- 
wick, f 
I am endeavouring to follow this good advice, and, while 
offering a tentative correlation of the various subdivisions of 
the Silurian rocks seen under Ingleborough with those of other 
areas, to avoid forcing a foreign nomenclature upon our district. 
In the case of the lowest divisions of the system, we shall see 
more clearly as we follow the details of the classification that 
we cannot identify bed for bed even within the limited distance 
from Ingleborough to the next outcrop of Silurian on the north, 
where the Rawthey and its tributaries have cut down to and 
exposed several clear sections in the Silurian rocks, but, if we 
regard the Avhole of the series which occurs at the base of the 
system, we find that it can be correlated with equivalent beds 
much further afield. 
In our examination of the palaeontology also, we must bear 
in mind that a small difference in the character of a deposit 
often determines what forms of life may be expected. We see 
this upon any shore. Cockles and mussels and whelks and 
purpuras, all have their own peculiar habitat. Yet, as an 
accidental occurrence we find a creature that loves the mud 
drifted away on to the sand, or one that lives on stones carried 
♦Continued from Proc. Yorks. Geol. Soc, vol. xv., p. 371, That part, 
pp. 351-371, should have been numbered Part iii. 
t Life, vol. i, p. 297, Trans. Geol. Soc, ser. ii, vol. iii. 
