132 PALAEONTOLOGY OF ILLINOIS. 



11. densTmmani, N. and W. Sub-carboniferous. 

 II. angulatus, N. and W. Sub-carboniferous. 

 II. gibbnsus, N. and W. Sub-carboniferous.* 

 //. placenta, N. and W. Sub-carboniferous. 



Genus COCHLIODUS, Ag. 



C. nobilis, N. and W. Sub-carboniferous. 

 C. crassus, N. and W. Sub-carboniferous. 



Genus ASPIDODUS, N. and W. 



A. crenulatus, N. and W. Sub-carboniferous. 

 A. convolutus, N. and W. Sub-carboniferous. 



Genus SANDALADUS, N. and W. 



S. Icevissimus, N. and W. Sub-carboniferous. 

 tS. carbonarius, N. and W. Coal Measures. 

 S. spatulatus, N. and W. Sub-carboniferous. 

 8. grandis, N. and W. Sub-carboniferous. 

 S. parvulus, N. and W. Sub-carboniferous. 

 8. angustus, N. and W. Sub-carboniferous. 



Genus PSAMMODUS, Ag. 



P. porosus, Ag. Sub-carboniferous. 



P. angular id, N. and W. Sub-carboniferous. 



P. rugosus, Ag. Sub-carboniferous. 



P. semicylindricus, N. and W. Sub-carboniferous. 



P. rhomboidevs, N. and W. Sub-carboniferous. 



P. reticulatus, N. and W. Sub-carboniferous. 



Genus TRIGONODUS, N. and W. 



T. major, N. and W. Sub-carboniferous. 

 T. minor, N. and W. Sub-carboniferous. 



