200 EXPLANATION OF PLATES. 



CONOCEPHALITES ANATINFS. 



Fig. 34. A glabella. 

 «« 35. A cheek, associated with the same. Three miles above Reed's landing, Lake 

 Pepin. 



CONOCEPHALITES DIADEMATUS. 



Fig. 86. A glabella : from Marine mills. 



«« 37. A larger glabella : from- Root river. 



«« 38. A cheek : from Root river. The outline in front a, shows the extension of 

 the '' doublure'^, or lower side of the frontal limb. 



CONOCEPHALITES WISCONSENSIS. 



Fig. 39. A head, with spine restored, in outline : from Trempaleau. 

 " 40. A part of a larger head : from Trempaleau. 

 " 41. A cheek, from Trempaleau. 

 «♦ 42. A spine, from Lake Pepin ( probably a cephalic spine of this species). 



■^ CONOCEPHALITES HAMULUS. 



Fig. 43. Glabella with spine : from Miniska. 

 <' 44. A spine (of Lonchocephalus), belonging to this species?? 



CONOCEPHALITES PATERSONI. 



Fig. 45. A small glabella. 

 *< 46. A large glabella. 



CONOCEPHALITES BINODOSUS. 



Fig. 47. A pygidium, with nodes, showing three segments besides the terminal one 

 in the axis, and three divided ribs besides the anterior articulation : axis 

 Tfide and strong. 



«« 48. A cheek of this species?, in the same rock at Osceola. 



DiKELOCEPHALUS ? 



Fig. 49. A pygidium with spines, the axis narrow; five articulations besides the ter- 

 minal ones; the lateral lobes with four or five annulations, and the anterior 

 ridge terminating in a border; the anterior margin curved and extended in 

 a spine. 



Arionellus bipunctatus. 



Fig. 50. Glabella and fixed cheeks, twice enlarged : from Root river. 

 «• 51. A cheek, twice enlarged : from Lawrence creek. 



Ill^nurus quadratus. 



Fig. 52. A glabella. 

 «♦ 53,54. Cheeks of difife rent individuals. 

 •« 55. A thoracic segment. 

 ♦♦ 56. A pygidium. 

 •« 57. A larger glabella. 



CONOCEPHALITES NACTUS ( n. S.). 



Fig. 58. A small species with ovate conical glabella which is marked by three distinct 

 pairs of furrows, the posterior ones of which extend obliquely backward 

 nearly to the occipital furrow. It is somewhat larger and less prominent 

 than C. minor, with a narrow occipital ring without spine. It occurs in the 

 lower beds of the sandstone near the mouth of Black river, Wisconsin. 



