212 Barrande on the Primordial Fauna and Taconic System. 
ticed in Mr. Barrande’s letter to Prof. Bronn have been found 
may be subordinate to the Potsdam it seems probable that the 
sequence contended for by Emmons will turn out to be at leas 
for the greater part the true one. 
it, 
On THE PrimorpiaL Fauna AND THE Taconic System or Emmons, IN A 
ETTER TO Pror. Bronn or Hewerserc.* 
“Paris, July 16, 1860. 
re i I have recently received, thanks to the kindness of Mr. E. Bil- 
lings, the learned palzontologist of the Geological Survey of Canada, a 
very interesting pamphlet entitled ‘Twelfth Annual Report of the Re- 
gents of the University of the State of New York, 1859.’ If you possess 
this publication, you will find there, at page 59, a memoir of Prof. J. Hall, 
entitled ‘ Trilobites of the Shales of the Hudson River Group.’ This sa- 
bo ag describes three species under the names Olenus Thompson, 
8 
i 
ion to be expected from so skillful and experienced a paleontologist as 
James Hall. 
ood en 
cies render sufficiently exact. The first is 105 millim. long by 80 broad, 
the other two are somewhat smaller, 
“The heads of the two Oleni being deteriorated, the furrows of the 
glabella cannot be recognized. The thorax has a common and remarka- 
ble character, which consists in the greater development of the third seg- 
ment, the point of which is stronger and longer than in all the other 
pleura. This is astriki 
* Proceed. Boston 8. N. Hist., vol. vii, Dec. 1860, p. 872. 
