332 



Explanation of the Plates. 



CONOCEPHALITES DIADEM ATUS. 



Fig. 36. A glabella : from Marine mills. 

 " 37. A larger glabella : from Root river. 



" 38. A cbeek : from Root river. The outline in front a, snows tbe 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 r from Miniska. 

 " 44. A spine (of Lonchocephaltjs), 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 wide and strong. 

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



DlKELOCEPHALUS OSCEOLA. 



Fig. 49. A pygidium with spines, the axis narrow ; five articulations besides the terminal one ; 



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 different individuals. 

 " 55. A thoracic segment. 

 " 56. A pygidium. 

 " 57. A larger glabella. 



CONOCEPHALITES NACTUS (n. S.). 



Fig. 58. A email 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 th« lower beds of the sandstone near the 

 mouth of Black river, Wisconsin. 



