650 THE LOWER SILURIAN PERIOD. 



the front of the glabella, and rising obliquely upwards and backwards 

 to ocular lobes, which are small and semi-lunar, folded considerably 

 upwards, and are situated just opposite middle of head ; width between 

 ocular lobes about equal to width in front. Behind the eye the 

 suture describes a long open sigmoid curve, which is continued inward 

 somewhat so as to give the limb a rounded outline, and make the cheek 

 here about one-third wider than at the eye. Posterior margin of 

 cheeks with a slight fold, more prominent in the middle ; outer half of 

 this margin is arched backwards. Whole head arched slightly for- 

 ward vertically. 



This species resembles C. Hallii, Hartt, but differs from it in the 

 shape of the anterior marginal furrow. This same feature and the 

 long and narrow glabella distinguish it from C. Robbii. Rather 

 common in shales at Ratcliffe's Millstream. — N. B. Survey, 1864, and 

 J. W. Hartt. 



Conocephalites elegans, Hartt, MS., Ratcliffe's Millstream. Head 

 or cephalic shield semi-circular or semi-elliptical, more than twice as 

 broad as long, nearly straight behind ; anterior border with a very 

 strong fold, separated from the rest of the head by a deep groove. 

 This fold is widest and most elevated just in front of the glabella, 

 where it is sometimes the tenth of an inch in width. At this point the 

 groove bends abruptly and angularly, and arches forward on each 

 side so as to encroach on the marginal fold and cause it to disappear 

 at about half the distance between the middle point in front and the 

 posterior angles of shield. The posterior marginal folds are very thin, 

 most elevated in the middle, and sloping each way towards the occi- 

 pital ring and posterior angles of shield. The axis of the outward half 

 is more and more inclined backward from the perpendicular towards 

 the posterior angles, which are rounded, more or less flattened, and 

 without backward projecting spines. The grooves separating the 

 posterior fold from the cheeks are very deep, and are slightly directed 

 forward. Length of glabella about six-tenths of antero-posterior 

 diameter of shield, a little wider at base than long, and less than half 

 as wide anteriorly ; triangular, with anterior part rather broadly 

 rounded, highly inflated, and bounded by deep grooves, which in front 

 join in with the anterior marginal groove. There are three pairs of 

 glabella furrows. Those of the posterior pair impress deeply the sides 

 of the glabella, are strongly curved backwards, and scarcely reach a 

 third of the distance across each side. The second and third pairs 

 only just impress in like manner the sides of the glabella. Those of 

 the second pair are curved backward, and extend about a quarter of 

 the distance across the glabella. Those of the third pair are very 



