17^ THE SILURIAN TR[L013ITES OF NEW SOUTH WALES, 



Cyphaspis yassensis is also remarkable for the great lateral 

 expansion of the ceplialic-siiield, as compared with the central 

 portion or glabella. This, with the general contour and the wide 

 anterior glabellar border (limb), strongly reminds us of the genus 

 Arethicsina. 



Loc. and Horizon. — Belle Vale, between Bowning and Yass, and 

 at Bowning, Co. Harden — Lower Trilobite bed, Bowning Series 

 (? Wenlock) (ColL Mitchell). 



Cyphaspis Horani, sp.nov. (PI. vii. figs. 4, ia-c). 



Sp. Char. — Body oval. Cephalic-shield subsemicircular, highly 

 inflated ; limb wide, divided into two almost equal parts, of which 

 that immediately in front of the glabella is subtumid and conspicu- 

 ously granulated, anterior part concave, edge thickened and bearing 

 a row of granules, subcrenated ; glabella ovoid or elliptical, very 

 tumid, highly granulated, glabellar grooves not present, axial 

 furrows deep and continuous in front ; circumscribed lobes small, 

 narrow and elongate, close to and somewhat under the sides of the 

 glabella; fixed cheeks fairly large, very tumid centrally, granu- 

 lated, the posterior granule largest ; eye lobes large, suboblong- 

 semicircular ; free cheeks very inflated, the inflated portion 

 ornamented with several rows of slightly oblique granules, and 

 subcrenulated, margin thickened; genal angles continued into long 

 slender falcate spines embracing and apparently reaching to or 

 near the extremity of the thorax ; eyes small, suboval or sub- 

 circular, in some specimens very prominent, facets not observed ; 

 facial sutures anteriorly comparatively straight, incurving on 

 edge of limb a short distance before passing out, posteriorly 

 sharply curved outwards and cutting the posterior margin of the 

 shield at the extremities of the side lobes; neck furrow deep, 

 wide, strongly arched backward, interrupted by circumscribed 

 lobes and continuing much less conspicuously across lateral lobes; 

 neck ring prominent, intensely arched backward, bearing a row of 

 granules of which the central one is most conspicuous. Thorax 

 consisting of ten segments, length equal to width, apparently 

 highly granulate ; axis prominent, proximal portion for six seg- 



