130 



Contributions to Palaeontology. 



" segments ( fig. 12, Tab. I A). The pygidium found 

 " associated in the same beds is semilunar, with little 

 " or no border, and has four segments of the axal lobe;" 

 The Genus Crepicephalus was created for other forms, 



of which Dr. Owen speaks as follows : 



" The rather fiat slipper-shaped glabella is tapering and 

 " slightly acuminated anteriorly, with a faint ridge in 

 " the median line : two small and very superficial de- 

 " pressions, and a posterior faint furrow, very partially 

 " divide the glabella. The facial sutures run nearly 

 "parallel to the margin of the glabella, and join a 

 " thickened cordlike anterior narrow border, enclosing 

 " a convex area, narrower in front than at the sides. 

 " Oblique plications can sometimes be traced on the 

 " cheek-plate in advance of the eye, converging towards 

 " the apex of the glabella." 



We observe here also characteristics of the Genus Co- 

 nocephalites in the conical glabella with obscure furrows, 

 and the ocular ridges in the obliqe plications, etc. ; while 

 the only species designated by Dr. Owen (C. ivisconsensis) 

 has a wide frontal limb, and offers no means of distinction 

 in the head from one species placed under the Genus Lon- 

 chocephalus (the L. hamulus). 



It is difficult and perhaps impracticable to sustain these 

 genera, or either of them, upon the characters here given ; 

 though it must be admitted that there is some difficulty 

 in referring all these species to Conocephalites, when we 

 restrict the signification to such forms as the C. sulzeri and 

 C. striatus. 



In several of our species the glabella is very depressed 

 convex, and the oblique furrows are wanting or very ob- 

 scure. It must be stated, however, that we are dealing 

 with the casts of the interior, and therefore these markings 

 are necessarily obscure. The presence of spines from the 

 occipital ring cannot of course be regarded as of generic 



