CRUSTACEA. 
143 
Cheeks elevated about the orbital node and sloping abruptly to the 
thickened margin. Palpebral lobes elevated; visual surface not observed. 
The Surface of the cephalon is ornamented by strong, scattered pustules 
which become obsolete upon the border and the genal spines. Upon the 
occipital ring is a single, strong, spiniform tubercle, generally accompanied 
by a smaller one on either side. The anterior and lateral margins of the 
cephalon bear two rows of strong spines, one above the other; those of the 
upper row being the longer and having their bases upon the proximal surface 
of the marginal rim. The proximal surface of this rim lies vertically upon 
the margins of the cheeks, and hence the spines which stand perpendicular to 
its surface, lie in the horizontal plane ; as it approaches the frontal margin 
this rim becomes turned upward and slightly reflexed, so that towards the 
anterior extremity the spines of the upper row stand at an angle of nearly 
forty-five degrees to the horizontal. The spines of the lower row are shorter, 
lying in the horizontal plane on the frontal margin, and deflected below the 
horizontal plane on the genal margins. Of these spines there are about 
eighteen in the upper and sixteen in the lower row. 
A single fragment of a thokax associated with a cephalon of this species, 
shows a very wide and gently arched axis, six narrow and flattened segments 
each bearing a number of strong pustules, of which there are two longitudinal 
rows upon the pleurae, and for each segment of the axis five or six pustules 
which do not appear to be arranged in longitudinal rows. This appearance 
may, however, be due to the imperfection of the specimen. 
Dimensions. Length of cephalon 4 mm.; width at the posterior margin 
7 mm.; length to the extremity of the genal spines 8 mm. 
Observations. The striking ornamentation of the cephalon of this species 
finds its analogue in Cyphaspis Cerberus, and C. Davidsoni, Barrande, from the 
etage F, and in C. coronata, Barrande, from the etage G. In these species there 
is but a single row of spines, which in C. Cerberus are short and numerous, in 
C. Davidsoni broad and stout, and in C. coronata more like the upper row of C. 
stephanophora, but fewer in number. 
