Gsoicgy Dept 



NOTICE. 



THE accompanying Monograph, by Professor Huxley and Mr. Salter, 

 shows the advantage accruing to geological science from the com- 

 bined efforts of the Naturalist and the Paleontologist. 



Having devoted many years of my life to the establishment of 

 the true order of those strata which are characterised by the genus 

 Pterygotus, i.e. the Upper Silurian Rocks of Britain and Russia, and 

 the Lower Old Red Sandstone of Scotland, it is peculiarly gratifying 

 to me to announce the issue of a work which, whilst it throws 

 fresh light on the organic remains of those deposits, and must be 

 valued by all naturalists, will at the same time sustain the useful- 

 ness of the study of fossil remains, in developing the true geological 

 structure of the British Isles. 



The figures and descriptions of British Organic Remains having 

 been hitherto, in great measure, confined to the illustration of 

 isolated genera and species, it was found convenient to publish 

 them, at intervals, in fasciculi of Ten, under the term of Decades. 

 That title is, however, obviously inapplicable to Memoirs like the 

 present, and to other Monographs containing a variable number 

 of plates, which are in preparation. 



RODEEICK I. MURCHISOX, 



December 31, 1858. Director-General* 



[1.] A 2 



ft 



* "S55815 



