vill ADVERTISEMENT TO SECOND FASCICULUS. 
English or French books, by the use of algebraic symbols, according to a practice partially 
introduced by some recent writers in Germany. The proportions of the shells have been 
expressed in fractions of the greatest absolute measurement, and the angles given in degrees by 
the goniometer, in accordance with the modern French practice, as more brief and precise than 
the ordinary use of indefinite expressions. 
Of the number of new species described in this work a general notion may be 
formed by a glance of the eye over the plates; as no species is here figured of which a 
good and sufficient figure has been before published. The description of the species and 
genera is full and luminous, and will, I trust, be found of great value to the paleontologist. 
The third and concluding Fasciculus will, I trust, be published before the end of this year, 
and to this I hope to prefix a short account of the English Palzozoic System, with com- 
parative and illustrative sections indicating the true relations of the successive groups in each 
system or series. 
ADAM SEDGWICK. 
TRINITY COLLEGE, 
July 16, 1852. 
