Contributions to Palaeontology. 



165 



the small tubercles at the extremities of the posterior lobes of the 

 glabella. 



Fig. 33, is from a cast taken in a mould of the exterior surface, showing 

 the striations ; but the eye-lobes are not visible (figure en- 

 larged). 



Fig. 34, is from a cast of the interior in sandstone. 

 Fig. 35, a profile of the same. 



Fig. 36. An enlarged figure from a small head of this species. 



Fig. 37. A cheek of this species. 



Fig. 38. Profile or lateral view of the same. 



Fig. 39. A part of a thoracic segment. 



Fig. 40. A pygidium found associated with this species, the form of which 

 corresponds to the one figured by Dr. Owen, Tab. 1, f. 5. 



This species occurs in the greenish gray beds of Trempaleau and 

 Miniska, in the central portion of the series, associated with Ptycha- 

 spis miniscaensis ) and in gray beds a little lower in the series, asso- 

 ciated with Agnostus josepha, Conocephalites wisconsensis and C. 

 anatinus. 



PTYCHASPIS (sp.?). 

 PLATE I. FIG. 48. 



The figure ( Plate i, fig. 48) is about three times enlarged, from 

 small specimen which possesses the characteristics of this genus. 



It appears to be an entire head, but no facial suture or eye-tuber- 

 cle can be distinguished. It is possible that it may be the very 

 young of P. miniscaensis. which, in all the smaller specimens, ap- 

 proaches the P. granulosa in its appearance. With a single speci- 

 men, I hesitate to characterize it as a distinct species. 



It occurs in the sandstone at Trempaleau, associated with P. 

 granulosa and Agnostus josepha. 



GENUS CHARIOCEPHALTJS ( n. g.). 



[ Gr. x a p'?> gratia ; xspaX^, caput."] 



Head broad; cheeks moderately convex towards the 

 eyes ; glabella regularly convex, and marked by trans- 

 verse furrows ; eyes large ; facial suture cutting the 

 contour of the front at or near the centre. Thorax un- 

 known. Pygidium ? 



