G54 THE LOWER SILURIAN PERIOD. 



thewi, but with wider and less elevated marginal folds, cheek-lobes 

 much more gibbous and semi-ovoid, etc. Sparsely sown with minute 

 spines, grouped two and two. Rare at St John. — C. F. and J. W. 

 Hartt. 



Fig. 227. ConocephalUes Hallii, Hartt, MS. (Fig. 227). Well 



separated from all the others by its very convex, nar- 

 row, and long glabella, ovate, or cylindro-conical ; 

 as well as by its strongly rounded sub-angular out- 

 Conocephalites ji^e in front, and by its peculiar anterior marginal 



Halliii:^). fQi^_ ^^^ common at Ratcliffe's Mill.— N. B. Survey 

 and J. W. Hartt. 



Conocephalites quadratiis^ Hartt, MS. Head minute, transversely 

 oblong, twice as long, slightly curved in front, straight behind, very 

 flat ; a narrow elevated fold, convex in front, concave behind, and 

 somewhat inclined backward, goes round the margin. Very rare at 

 Coldbrook. — Mr Matthew's cabinet. 



Conocephalites neglectus, Hartt, MS. Glabella regularly semi- 

 elliptical ; length, exclusive of occipital ring, about two-thirds of 

 width at base, moderately convex. Highest at middle of base and 

 sloping with a regular curve toward the front. Traces of two pairs of 

 glabella furrows on the sides. Occipital furrow deep and concave. 

 Occipital ring with straight parallel margins, narrow with a short 

 conical spine directed upward, etc. Very rare at Coldbrook. — 

 Mr Matthew's cabinet. 



Conocephalites formosus, Hartt, MS. Head trapezoidal in outline, 

 the anterior and posterior margins approximately parallel, and the 

 former of less extension than the latter. Glabella as wide at occipital 

 furrow as long, narrowed in fi'ont, and broadly rounded, with straight 

 sides, — three transverse furrows dividing it into almost equal parts, 

 etc. Not very common, Ratcliffe's Mill. 



Conocephalites^ n. s. (?), Hartt, MS. Resembles C. tener^ but has 

 much shorter head and glabella, and very high anterior marginal 

 fold. Very rare at Ratcliffe's Mill. 



Microdiscus Dawsoni, Hartt, MS. (Fig. 228). Cephalic shield 

 semi-lunar, with thickened border crossed by numerous grooves run- 

 Fie 228 ning perpendicularly to the circumference. Glabella convex, 

 narrow, rounded in front, conical and pointed behind, pro- 

 jecting beyond posterior border, without furrows or occipital 

 Microdiscus cri-oove. Checks convex, no eyes, and no traces of sutures. 



Daiustmi, head, ^ , .... ... 



mag. Posterior angles of shield with backward projectnig spines. 

 Pygidiuin sub-triangular, Avitli curved outlines, rounded in 

 front and behind. Middle lobe distinctly marked, and divided 



