186                                                  SILUEIA.                                       [Chap. IX.
 

CHAPTEE IX.

OEGANIC EEMAINS OF THE LOWEE SILUEIAN EOCKS.

A PTiLL acquaintance with the SUurian Eossils of the British Isles can be
gained only by a study of the various works in which they have been
successively described. Of these works, the first in which the fossUs were
classified and placed in their true geological position is the ^ SUurian
System' *; the next is a Eeport on the Silurian fossUs of Tyrone, by
Portlock; a third, on the SUurian fossUs of Ireland, by M'Coy. Then
foUow various publications of the Government Geological Survey, par¬
ticularly the volume on the Malvern and Abberley HiUs, by Professor
Phillips and Mr. Salter, certain monographs descriptive of both Lower
and Upper Silurian forms, m the Decades of the Geological Survey, by the
late Professor E. Eorbes and Mr. Salter, and the Appendix by Mr. Salter
to Professor Eamsay's 'Geology of North Wales' (Mem. Geol. Surv. vol.
in.). Notices of SUurian fossUs have also been published by Mr. D.
Sharpe, Mr. Salter, and other writers in the volumes of the Quarterly
Journal of the Geological Society of London. A detaUed description of
the Upper SUuiian Brachiopods, by Mr. Davidson, appeared in the Bul¬
letin of the Geological Society of Erance, nearly aU the British species
being there figured and described. In the Introduction to his Monograph
of British EossU Brachiopods (vol. i.), Mr. Davidson has described their
generic characters; and his special Monograph on the SUurian Brachio¬
pods, published by the Ealaeontographical Society, is a work of the highest
order of merit. Three parts of Mr. Salter's Monograph of the British Tri¬
lobites have also been pubhshed by the same Society. Professor Eupert
Jones has described most of the smaU Bivalved Crustaceans of the SUurian
rocks, in the * Annals of Natural History.' Lastly, an important addition
has been made to our knowledge of the British fossUs of this age through
the pubhcation, by Professor Sedgwick, of Professor M'Coy's descriptions
of the Palfeozoic fossUs in the Woodwardian Museum of Cambridge. This
work, to which references are often made hi the present volume, contains ela¬
borate descriptions of upwards of 300 species, with figures of the new forms.
The reader who consults these various worksf wiU find that, whUst
a marked division was at first particularly insisted on, by myself, as ex¬
isting between the Lower and Upper Silurian, subsequent researches,
extended over large areas, have shown that the two groups are much more
closely knit together in one natural series than was formerly supposed,—
it being now well ascertained, as already explained, that a considerable

* The Shells of the ' Silurian System ' were de-        t In the ' Geologist,' vol. i., 1858, Prof Morris

scribed by James de C. Sowerby, who had pre-     publisheda very useful List of Books and Memoirs

viously figured and described some of the species     relating to Silurian and Cambrian Geology, com-

in his ' Mineral Conchology.'    The latter were     plete to that date,
chiefly from the Wenlock Limestone.