BY R. ETHERIDGE^ JUNR.^ AND JOHN MITCHELL. 667 



There is a close similarity between this species and the Tas- 

 manian form erroneously named Cromus viurchiso7ii, De Kon., 

 by one of us, and already referred to. It is possible the two 

 may be identical. • 



Log. and Nor. — Silverdale, Limestone Creek, and doubtfully 

 from Bowning Creek, Parish Bowning, County Harden. Lower 

 Trilobite Bed = Upper Silurian (Wenlock), Coll. J.M. Hardy's 

 or Limestone Creek, Parish Derrengullen, County King. (Coll. 

 Aust. Mus.; A. J. Shearsby). 



ExcRiNURUS ETHERiDGEi, f^p.noi\ (Mitchell). 

 (Pl.liv.,fio-.13; Pl.lv., figs.7,8,10,11.; Pl.lvi., %.9; Pl.lvii., figs.l, 

 2,4,8.) 



Sp. Chars. — Complete form elongately oval. Cpphalon subsemi- 

 circular, rugo-tuberculate, approximately length equal to the 

 width between the genal angles, or as long as nine thoracic seg- 

 ments. Glabella elongately pyriform, tapering from the anterior 

 pair of axial tubercles forward to a rather acute point, giving it a 

 mucronate appearance when the free cheeks are absent, tuber- 

 culate, tubercles rather small and subeven in size, the five pairs 

 of axial tubercles very even in size and distinctness, the second, 

 third, and fourth pairs, as is usual with other species, the most 

 distinct. Neck-furrow moderately distinct, its extension across 

 the posterior border of the fixed cheeks similarly so. Neck- 

 annulation narrow and prominently arched, its lateral extension 

 narrow. Axial furrows narrow and deep; fixed cheeks tumid, 

 rather small, faintly tuberculate; axial tubercles only moderately 

 distinct, rugoid, and between the eye-lobe and the posterior 

 furrow arranged in three irregular rows, which, towards the genal 

 angle, converge to one; genal angles rounded and only slightly 

 thickened, sulci of the eye-lobes distinct. Free cheeks large, 

 tuberculation similar to that of the fixed cheeks, border and 

 furrow pronounced; eyes very prominent, conical, pedunculate, 

 and surrounded by sulci. Facial sutures of the usual character. 



Thorax subrectangular, length approximately two-thirds the 

 wddth, very lightly if at all granulate; axis almost of uniform 

 width throughout, arched transversely and anteriorly, basal ends 



