Victorian Fossils, Part XVII J. L66- 



than that of the free cheeks and nearly equal throughout. Side 

 lobes three, the posterior moderately large, the median small and 

 the anterior hardly developed. Frontal lobe prominent; the an- 

 terior limb quadrate and deeply furrowed behind. Neck furrow 

 deep, and continued to the slightly rounded genal angles. Free 

 cheeks i:il>l>ous, usually not so inflated as the glabella. Eyes situ- 

 ated on the elevated portion of the free cheeks and slightly anterior 

 to the middle lobe of the glabella. Furrows between glabella and 

 free cheeks deep. Neck ring thick in middle, thinning out later- 

 ally. 



Thorax. — The body axis is of about the same width as the pleura, 

 and at the sides invariably thickened into tubercles. Axis rings 

 deeply furrowed. Fulcra of pleura situated about half-way to the 

 lateral border; ends posteriorly rounded and bent forward. Pleura 

 deeply ridged. 



Pygidium almost semi-circular, strongly convex. The axis is 

 deeply incised at the junction with the lateral ribs. Axial rings 

 gently arched. The prominent lateral ribs are medially furrowed 

 half-way to the margin. Surface of carapace finely tuberculate. 

 apparently with granules of one size. 



Dimensions. — Total length of holotype, 54 mm. ; made up as fol- 

 lows : — Cephalon, 17.5 mm.; thorax. 25 mm.; pygidium, 11.5 mm. 

 (these measurements are approximate, especially for the thorax. 

 which has undergone compression and recurvation); width of 

 cephalon between genal angles, 39 mm. 



Relationships. — This species show relationship to two British 

 forms. C. tuberculosa, Dalman, 1 and G. blumenbachi, Brongniart. 2 

 as well as to a North America species, G. niagarensis . 3 The narrow, 

 elongated glabella and the deep and extended neck furrow separate 

 the Victorian species from G. tuberculosa, the glabella hi that form 

 being short and anteriorly tapering. The lateral riblets of the 

 pygidium in G. angustior arc furrowed or bifurcated distally, but 

 in G. tuberculosa they are simple. In both species the lateral ends 

 of the axial rings of the thorax are tuberculate. 



In the latter feature, C. niagarensis is related to the Victorian, 



1 C. blumenbachii, var. a, tuberculosa, Dalman, Ueber die Paliiaden Oder die sogenannten Tril- 

 obiten, a. d. Schwedischen iibersetzt von Fr. Engelhard, 1828. 



C. tuberculosa, Dalman, Salter, Mem. Geol. Surv. Gt. Brit., vol. ii., pt. i., 1818, p. 342, pi. xii. 



2 C. blumenbachii, Brongniart, Crust. foss., vol. ii., pt. i., 1822, pi. i., fig. 1A-C. Barrande, Syst 

 Sil. Boheme, vol. i., 1852, p. 566, pi. xix., fig. 10; pi. xliii., figs. 46-48. Brit. Trilob. (Pal. Soc. 

 Mon.), pt. ii., 1865, p. 93, pi. viii., figs. 7-16 ; pi. ix., figs. 1, 2. 



3 C. niagarensis, J. Hall. Geol. N. York, pt. 4, 1843, p. 102, fig. 3. Weller, Bull. Chicago 

 Acad. Sci., No. iv., pt. ii., 1907, p. 261, pi. xxiii., figs. 9, 10. 12b 



