4:88 SILURIAX TRILOBITES OF NEW SOUTH WALES, vi., 



Crossing (not in situ). Parish Kast Goodradigbee, County Cowley, 

 or Parish West Goodradigbee, County Buccleiich : and from 

 "near Yass," but probably from the black Cave Limestone, 

 Cave Flat, Muirumbidgee, Parish (yliildowla, County Harden. 

 Probably Upper Silurian. 



Genus Cheiruhus Beyrich, 1845. 



(Ueber Bohmischen Trilobiten, \8ib. fide Barrande). 



Section Crotaloce]ihalus Salter, 1853. 



(Mem. Geol. Survey Gt. Brit., Dec vii (ii.), 1853, p.lO). 



"Glabella broadest in front, with furrows continuous across. 

 Bc^dy rings 11, nodular.' 



Crotalocephabis was proposed by Salter, in 1853, as a sub- 

 genus, occurring in the Devonian and Upper Silurian. One 

 British species (C. articulalus Minister) occurs in the Devonian, 

 and is about half the size of the Bowning form, with a much 

 more rounded frontal lobe, and no dip in the centre of the an- 

 terior furrow. 



The Bowning fossil is closely allied to three Upper Silurian 

 species — C. quenstedti Barr., C. sternheryi Boeck, and 6'. gibbus 

 Bevrich -in the divisions of the glabella, and to some extent in 

 its outline. Of the three, it approaches nearest to C. quenstedti. 



The relation of the Bowning fossil to these really turns on the 

 number of thoracic somites: C. qaeiistedti lias 11, 6'. gibbus 9, 

 and, in C. sternbeiyi, the number is unknown. The Bowning 

 species has eleven, and agrees in that with C. quenstedti. The 

 pleune are quite different from those of either of the above. 



Ilistori/. — The first intimation we possess of the occurrence 

 of this genus in Australia, we owe to Dr. A. R. C. Selwyn, 

 through specimens found by the Geological Survey of Victoria 

 at Keilor, near Melbourne, Yerring on the Upper Yarra, and at 

 VVoori-Yallock Creek junction with the Yarra River;* these 

 were doubtless determined by Prof. F. McCoy. Mr. J. W. 

 Salter included the genus in his list of " Fossils of the Southern 

 Districts" of New South Wales as C. murrayi.j We do not 



* Selwyn, Quart. Journ. Geol. See, xiv., 1858, pp. 537-8. 

 t Clarke, S. Goldfields of N. S. Wales, 1860, p. 286. 



