Figs. 
Figs. 
Figs. 
Figs. 
46 and 47. 
48 to 50. 
51 to ‘54. 
51 and 82. 
53 and 54. 
55 and 56. 
O: (DD SUB QUATA Var: CIRCULARIS N: H. Winchell ..5:..5..2. 0.0.22 scncevee selec 
Two views of the type specimen of Orthis circularis Winchell, a brachial and 
profile. Trenton shales, Oxford Mills, Goodhue county, Minn. Minnesota 
Geological Survey collection. 
ORTHIS (DALMANELLA) AM@NA N. H. Winchell .... 62.0020. oe cece cence cw lene 
Dorsal, profile and cardinal views of the type specimen. ?Galena limestone, 
Spring Valley, Minn. Minnesota Geological Survey collection. 
PLATYSTROPHIA  BIFORATA SCHIOGHEIM, (Spill sss. clove clecls aielsleieid clo ele e+ cicisins sieve 
Ventral and cardinal views of a large specimen. 
Dorsal and profile views of a specimen of the ordinary size. Galena shales, 
Goodhue county, Minn. Collections of W. H. Scofield and C. Schuchert. 
PLATYSTROPHIA BIFORATA Var. CRASSA JaMES............ seas eecstecesceerscsears 
Ventral and profile views of a nearly globose specimen. Hudson River group, 
Spring Valley, Minn. Collection of C. Schuchert. 
453 
458 
