NO. 13 DIKELOCEPHALUS AND OTHER GENERA 37I 



consin ; also. (86b) hilltop, north end of city of Lansing, Allam- 

 akee County, Iowa ( P. Bartsch, 191 2) . 



Also from locality (83'), an upper horizon of the St. Lawrence 

 formation near Trempealeau, Trempealeau County (Cooper Curtice 

 and G. H. Squiers, 1884; Chas. Schuchert, 1893) ; (113) at La 

 Grange Mountain (or Barn Blufif), near Red Wing, Goodhue County 

 (Cooper Curtice, 1884) '• (^5^) bank of St. Croix River. Stillwater. 

 \\'ashington County, all in ]\Iinnesota. 



Doubtful identifications. — From the upper beds of the old " St. 

 Croix sandstone," or St. Lawrence formation. 



(3390 Among fragments from the Copper Cambrian sandstones 

 at ]\linneiska, Minnesota, on the Mississippi River, there is one of a 

 large thoracic segment that may belong to this or an allied species. 



At Localities 78 and 78b, Osceola, Wisconsin, a somewhat similar 

 segment and a fragment of a large cranidium (pi. 62, figs. 4, 6) indi- 

 cate that a large species is present. Better specimens may prove that 

 the material belongs to a distinct and undescribed species or to Dikelo- 

 ccphalus limbatus. 



( 78) Lpper Cambrian : St. Lawrence sandstone series ; quarry 

 near St. Croix River, in suburbs of Osceola, Polk County (L. C. 

 Wooster, 1883), and (78b) 50 feet (15.2 m.) above St. Croix 

 River, near the landing at Osceola, Polk County (Cooper Curtice, 

 1884) , both in Wisconsin ; also (339f ) near Minneiska (Miniska) , on 

 Mississippi River, near the line between Wabasha and Winona 

 counties, Minnesota (F. M. Brown). 



DIKELOCEPHALUS MINNESOTENSIS var. 

 Plate 61, fig. 4 



A variety of D. minnesotensis occurs at La Grange mountain 

 (Locality 113) that is represented by the pygidium illustrated by 

 figure 4, plate 61. This has four rings on the median lobe and four 

 segments outlined on the pleural lobes, while D. minnesotensis has 

 seven or eight rings on the median lobe and eight or ten segments 

 outlined on the pleural lobes (pi. 61, fig. 6). A second pygidium 

 possibly of this variety comes from Osceola at a horizon higher as 

 indicated by the associated fauna. 



Formation and locality. — Upper Cambrian : St. Lawrence forma- 

 tion ; (113) sandstone at La Grange Mountain (or Barn Blufif), near 

 Red Wing, Goodhue County, Minnesota (Cooper Curtice. 1884), 

 and ( 78b) 50 feet ( 15.2 m.) above the St. Croix River, near the land- 

 ing at Osceola, Polk County, Wisconsin (Cooper Curtice. 1884). 



