404 



Description. Head apparently semicircular ; anterior margin strength- 

 ened by a narrow convex rim a little more than its own width from the 

 front of the glabella, just within which is a curved row of punctures with 

 fine striae as in D. Oweni. Glabella elongate conical, depressed convex, 

 front rounded, sides nearly straight, slightly converging from behind forward 

 Neck furrow straight in the middle, turned slightly forwards towards the 

 ends. In front of this, two other short furrows on each side dividing the 

 glabella into three lobes of which the anterior is the largest ; the posterior 

 furrows sometimes obscurely connected on the median line their outer 

 extremities directed forwards at an angle of 45 with the longitudinal axis 

 of the body ; the anterior pair nearly at right angles, but sloping a little 

 forwards, their inner extremities not connected. On the front lobe there 

 appear to be indications of a third pair of furrows on one of the specimens. 

 The eyes are semi-annular, nearly half the whole length of the head, their 

 anterior corners a little in advance of the outer extremities of the anterior 

 glabellar furrow ; their centres distant from the sides of the glabella, one- 

 third the width of the neck segment, their upper and lower angles, half 

 that distance. Surface, except the striated front margin apparently 

 smooth. 



Cheeks, thorax and pygidium unknown. 



Length of largest head seen five lines and a half ; of glabella four lines 

 and a half; width of glabella at neck segment three lines and a half 

 nearly, and at front furrows three lines. 



Limestone, No. 1. 



DlKELOCEPHALUS CRISTATUS. (N. Sp.) 

 Fig. 381. 



Description. Small, head apparently semi-circular; front margin with 

 a strong rim abruptly elevated on its posterior edge and thence descending 

 with a flat slope to the anterior edge, distant about its own width from the 

 front of the glabella, with a row of punctures as in D. Oweni. Glabella 

 oblong, front and sides somewhat straight, anterior angles rounded, neck 

 segment and furrow well defined, no glabellar furrows. The glabella just 

 in front of the neck furrow is abruptly elevated into a sharp rounded roof- 

 shaped ridge from which it descends with a flat or gently concave slope to 

 the front and lateral margins. Eyes very large, full one half the whole 

 length of the head, their posterior angles close to the glabella at the neck 

 furrow ; thence they curve outwards so that their centres are distant from 

 the sides of the glabella rather more than one third the width of the neck 

 segment, thence more gradually curving inwards they reach the sides of 

 the glabella (nearly) at a point a "little in advance of its length. 



