FOSSILS OF THE ACADIAN GROUP. 653 



extremities of cheek sutures equal to or about twice width of glabella 

 at base. Cheek-lobes but slightly convex, and much more depressed 

 than the glabella. Ocular ridges very distinct, thin, .sharp, elevated 

 ridges, that begin about inner edge of cheek-lobes, just behind 

 rounded front of glabella, run outward and backward at an angle of 

 60° — 65° to the antero-posterior diameter. They are at first straight, 

 but soon begin to bend backward more and more abruptly, forming a 

 fragment of a spiral, their extremities being slightly directed inwards. 

 The width between the ocular lobes is about equal to twice the length 

 of the glabella. The ocular ridges are inclined outwards and forwards. 

 Another ridge of the same appearance begins a very shoii distance 

 behind the origin of the former, and on the very margin of the cheek- 

 lobes, and, diverging from the margin nearly opposite to the base of the 

 glabella, bends off abruptly along the posterior margin of the cheek- 

 lobe, describing a curve, whose convexity is directed backwards. 

 This ridge terminates considerably outside of the ocular lobe at a 

 point distant from the glabella about equal to half the width of the 

 latter at its base. This ridge is usually found inclined in the opposite 

 direction to the former, viz., inward and backward. Posterior mar- 

 gin of fixed cheeks moderately and regularly S-curved, the inner 

 halves curving forwards, the outer halves backwards, with a marginal 

 fold most elevated in the middle, but much less so than the ridges of 

 the cheek-lobe or the anterior fold. This fold becomes double at 

 about the middle, by the appearance of a groove running along its 

 summit, and it appears to run out before reaching the lateral suture. 

 The width between the posterior extremities of cheek-sutures is con- 

 siderably greater than between the anterior extremities or between 

 the ocular lobes. Glabella without furrows. 



This beautiful species I have found only in breaking up some 

 fragments of fine dark shale sent me from Coldbrook by my friend 

 G. F. Matthew. It is associated with Microdiscus Dawsoni, and 

 Paradoxides lainellatus. 



Conocephalites Aurora, Hartt, MS. Resembles C. Ouangondianum, 

 but differs in wider head, more depressed, anterior margin more 

 broadly rounded, and border more strongly reflexed and elevated, 

 etc. Rare at Ratcliffe's Mill. — N. B. Survey and C. F. Hartt. 



Conocephalites Thersttes, Ilartt, MS. Differs from the last and 

 also from C. Ouangondianum in the front margin being broad and 

 flat, and bordered by a low narrow flattened fold or ridge, etc. 

 Glabella in the cast has three pairs of very short raised lines on the 

 sides. Very rare at Ratcliffe's Mill. — J. W. Ilartt. 



Conocephalites gemini-spinosus, Hartt, MS. Resembles C. Mat- 



