84 ROYAL SOCIETY OF CANADA 



ol" the glabella, the marginal fold being the wider of the two. Glabella 

 conical, bluntly jiointed in the anterior quarter. The glabella and occi- 

 pital ring together are about as long as half of the space between the 

 facial sutures in front. The glabella has three pairs of furrows plainly 

 shown, and a fourth ])air faintly indicated. The furrows do not connect 

 across the axis. The occi^iital furrow and ring are not well preserved in 

 the specimens known, but the furrow appears to extend quite across the 

 back of the glabella. The tixed cheek is broad and flat, with a strongly 

 arched eye-lobe, about halfway between the side of the glabella and the 

 edge of the head-shield. 



The movable cheek is wide and strongly arched in the anterior part, 

 becoming straighter behind. The area is about half of the width of the 

 marginal fold in front, but less than that at the eye-lobe. The jiosterior 

 margin is sinuate, having a strong sinus near the genal spine ; and the 

 furrow and fold are broad and weak. The genal spine is narrow, and 

 more than twice as long as the movable cheek. The facial suture along 

 the eye-lobe is somewhat shorter ? than behind it, and not quite so long 

 as the anterior extension of the suture. This goes forward from the eyes 

 with a sigmoid curve, to the nearest part of the anterior margin. The 

 posterior extension of the suture is obscure in all the specimens obtained, 

 but a detached free cheek appears to indicate that it was nearly direct to 

 the posterior margin. 



Only detached segments of the thorax are known ; they have a 

 narrow rachis (compared with the width of the head) and short pleura ; 

 the latter is traversed by a strong furrow, which in some (the anterior) 

 runs along the centre of the pleura, but in others begins toward the front 

 side, and is more oblique ; the pleura arc bluntly pointed. 



The numbei" of segments is not known, but it may be assumed that 

 they were numerous. In some pleura^ the ring has a tubercle or fractured 

 base of a s})ine, on the posterior edge ; it is supposed that there was a 

 slender axial spine at the back edge of each thoracic I'ing, as such spines 

 are found on the joints of the pygidium. 



The pygidium is elongate semi-circular with a rather flat axis ex- 

 tending two-thirds of its length ; three joints are present in the axis, of 

 which the middle one bears a slender spine at the back; an appressed 

 spine, which extends across the anterior joint, appears to belong to the 

 posterior joint of the thorax. The side lobes are convex, and are of 

 nearly equal width, except at the back. The margin is entire, except that 

 it is notched behind at the axial line. 



Fragments of the hypostome have been found, but are not sufficient 

 for description. 



Sculpture. — The surface of the marginal fold of the movable cheek 

 is marked by widely spread, anastomosing, raised lines; along the front 

 margin of the shield, close to the edge, a few of these lines appear, but 



