FOSSILS OF THE ACADIAN GROUP. 649 



Occipital ring narrcvv, convex, widest iu the middle, narrowing 

 towards sides, which are turned forward, giving to it a crescent shape. 

 Occipital furrow deep and well developed, widest in the middle, where 

 it slightly impresses the base of the glabella; narrow and slightly 

 bent forward at the ends. The ring bears a little short conical 

 tubercle-like spine in the middle, directed slightly backwards. 



Fixed cheeks, frontal limb one-third to one-fourth of whole length 

 of head, with a narrow, high, convex border, inside of which is a 

 moderately deep furrow ; cheek-lobes depressed, convex, meeting in 

 front, rising abruptly from the deep dorsal furrow, on the borders 

 of which they reach their greatest elevation, which, however, is 

 not equal to that of glabella, and sloping thence roundly towards 

 the sides and front. The posterior limb bears a deep, wide, furrow, 

 which widens somewhat near extremity. The marginal fold is very 

 narrow and of little prominence ; and widens a little in the outer half. 

 The posterior margin bends slightly backwards at extremity of limb, 

 which is rounded. RatclifFe's Millstream.— N. B. Survey and J. W. 

 Hartt. 



Conocephalites Orestes, Hartt, MS. (Fig. 225). Tlie head-shield 

 of this species without movable cheeks is of medium size, length 

 about equal to breadth in front, or to two-thirds „. 



. . Fig. 225. 



width behind ; margin arched moderately in front, 



with a rather wide, low border fold, widest in front, 



narrowing toward the sides, separated from the rest 



of the head by a shallow groove. Glabella long, 



ovate, conical, or cylindrico-conical, extremely (-'<'»occ2>hahfes 



convex, wider behind than in front, where it is ' ' 



rounded. The sides are straight, and so inclined to one another as 



to meet, if produced, at a distance in advance of margin in front about 



equal to the distance of that line from glabella. The glabella is 



flattened on the sides, and never regularly convex. 



There are three pairs of furrows, which lightly impress the sides of 

 the glabella, and of which traces are not always distinctly preserved • 

 and they are apt to be seen best in slightly distorted specimens. Dorsal 

 furrow narrow, deep, and sharply cut ; occipital ring widest in the 

 middle, narrowed from behind at the sides, separated from glabella 

 by a distinct furrow. Bears in the middle a minute tubercular spine 

 pointing upwards. Fixed cheeks strongly convex, but much less so 

 than the glabella, meeting in front witli abrupt slopes toward dorsal 

 and posterior marginal furrows, but with gentle rounded slopes 

 toward sides and anterior groove. Ocular ridges, marked as lightly 

 raised lines, originating at the dorsal furrow some distance behind 



