CRUSTACEA. L43 



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 l>y 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 thorax 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. 



