138 BULLETIN OF THE NATURAL HISTORY SOCIETY. 



nearly half as wide as the glabella, both widen on each side of the 

 glabella, so that at the facial suture they are as wide as three 

 •quarters of the width of the glabella, the marginal fold being the 

 wider of the two. Glabella conical, bluntly pointed in the anterior 

 quarter. The glabella and occipital ring together are about as long 

 as half of the space between the facial sutures in front. The gla- 

 bella has three pairs of furrows plainly shown, and a fourth pair 

 faintly indicated. The furrows do not connect across ths axis. The 

 ■occipital 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 fixed cheek is broad and fiat, with a strongly arched 

 eyelobe, 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 eyelobe. The 

 posterior 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 eyelobe 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 ob- 

 scure 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 nar- 

 row rachis and short pleura; the latter is traversed by a strong farrow, 

 which in some (the anterior) run along the centre of the pleura, but 

 in others begins towards the front side, and is more oblique; the pleura 

 are bluntly pointed. 



In the restorationof the thorax given in Plate ///the anterior pleurae 

 arc longer than some examples would indicate, and the thorax wider: 

 the number of segments is not known, but it may be assumed that 

 they were numerous. In some pleune the ring has a tubercle or 

 fractured base of a spine, on the posterior edge; it is supposed that 

 there was a slender axial spine at the back edge of each thoracic 

 ring, as such spines are found on the joints of the pygidiura. 



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

 extending 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 ap- 



