ON A NEW TRILOBITE EROM BOWNING. 



By John Mitchell. 



[Plate XVI. (of Yol. IT. (2)), figs. 7-12]. 



ACIDASPIS LONGISPINIS, n.sp. 



Head-shield sub-semicircular, rather flattened in front, sparingly 

 granulated. 



Glabella less complicated than it usually is in members of this 

 genus; the central lobe somewhat oblong in shape, moderately 

 arched, and having on each side of it four tuberous elevations 

 separated from it by fairly defined grooves, and from each other by 

 shallow depressions. The anterior and posterior swelling on each 

 side is much less than the medial two on each side. From the neck 

 extend two long spines which appear to be equal in length to that of 

 the thorax and pygidium taken together, if not actually longer. 

 The eye-lobe is sharply angular ; the facial suture from the eye 

 to the front mai-gin almost straight, making with it an angle of 

 about 120° ; the posterior portion straight, cutting the base of the 

 glabella at the outer margin and making with it an angle of about 

 45°. Along the anterior lines of the facial sutures the edges of the 

 glabella seem to be bifurcate, forming a kind of socket for the 

 free cheek to rest in. 



The free cheeks bear very large spines at their genal angles ', 

 the outer margins slightly flattened, and extending from the front 

 towards the eye three rows of regularly placed granulations are 

 visible. 



The eye is almost sessile, conoid, and facetted, the latter 

 feature being remarkable. The posterior edge of the cephalic- 

 shield along the line of articulation with the thorax thickens 

 towards the extremities. 



