38 
Horizon and Locality. — Mr. Clarke foimcl this species at Eock Plat 
Creek in an argillaceous rock, yellowisli-oclire in colour, rather friable in some 
parts, harder and schistose in others. It is associated with Cromus holiernicus 
and several other Crustacea. I allow myself the great pleasure of dedicating 
this species to the indefatigable pioneer of civilisation and science to whom I 
owe its knowledge. 
CHEIEURUS, Leyricli} 
Cheirtjrus insignis, Beyrich. 
CheirurUS insignis, Beyrich, 1845, TJeber Bolim. Trilob., p. 12, fig. 1. 
,, ,, Barrande, 1846, Not. Prelim, sur les Trilob., p. 49. 
ChirurUS ,, Hawle and Corda, 1847, Prodr. einer Mon. Bobm. Trilob., p. 133, pi. 6, 
fig. 7. 
Ceraurus „ J. Hall, 1851, Pal. N. Tort, II, pp. 300, 306, pi. a66, fig. 4, and 67, 
fig. 9 and 10. 
Cheirurus ,, J. Barrande, 1852, Syst. Sil. Bobeme, I, p. 782, pi. 41, fig. 1-13. 
A solitary pygidium of this important species was found among the 
numerous fragments of Trilohites collected by the Eev. W. B. Clarke. It is 
so similar to the specimen figured by Barrande in his wonderful work, 
“ Systeme Silurien du Centre de la Boheme,” vol. I, plate xlv., fig. 8, that it 
is impossible to he mistaken in its determination. This species is distinguished 
from most of its congeners by the form of the pygidium and pleuras, which 
are four in number, the last jiair of which are represented by a pointed 
rudimentary one, which follows the direction of the axis. This last character 
is particularly well-developed in the Australian specimen. 
Horizon and Localities. — According to Barrande this species is one of 
a small number of Trilohites which are found in the two divisions of the 
Bohemian Silurian. 
In Australia it is found at Yarralumla in a brownish argillaceous rock, 
somewhat compact, and which can he scratched by the nail, associated with 
Stropliomenes pecten, Linnaeus and Cromus holiemicus, Barrande, species that 
help to fix the age to which they belong. 
o Procs. Linn. Soc. N. S. Wales, 1879, iii, Pt. 1, p. 30, pi. 6, figs. 5, G, 7 ; op. cit., 
Pt. 3, p. 217, pi. 6, fig. 8, pi. 17, fig. 7.-W.S.D.] . i , F > o , > . i 
