PAGE. 

 Figs. 30 to 34 LIOSPIRA OBTUSA U. and S 997 



30 to 32 Three views of a large specimen, chiefly a cast of the interior, showing the 

 obtuse periphery and in figure 32 the great thickness of the shell in the 

 umbilical region. The latter, however, seems never to have been completely 

 filled, a small perforation occurring in every case. Stones River group, Dixon, 

 Illinois. 



33 and 34 Profile and sectional views of a smaller specimen, the latter showing the 

 umbilical perforation. Geological and Natural History Survey of Minnesota, 

 Museum Register No. 687. 



Figs. 35 to 37 LIOSPIRA ANGUSTATA U. and S 997 



' SIT also plate I.MX.I 



35 and 36 Two views of a large specimen retaining considerable of the shell. Fusispira 

 bed, Trenton group, Wykofl, Minnesota. 



37 Vertical section of a small specimen showing narrow umbilical perforation and 



rapidly increasing shell surrounding it; from same locality. 



Figs. 38 to 44 LIOSPIRA PKOGNE Billings sp 996 



38 Under side of a specimen from the Fusispira bed of the Trenton group at 



Wykoff, Minnesota. This specimen presents the usual appearance of the 

 species as it occurs in Minnesota. Of the shell it retains only the concave 

 solid tilling of the umbilicus. 



39 Profile view in outline of a rather small silicifled shell, showing the peripheral 



band. The sutures are very indistinct and the surface quite smooth. Lower 

 division of the Stones River group, Murfreesboro, Tennessee. 



40 Vertical section of a typical specimen from the Trenton at Burgin, Kentucky. 



41 and 42 Basal and profile views of the solid axis of a large specimen. Trenton group, 

 Hartsville, Tennessee. 



43 Under side of another axis in which the callosity which fills the umbilicus is 



more distinctly outlined than usual. 



44 Another Tennessee specimen in which the umbilical cavity is unusually narrow. 



Figs. 45 to 47 LIOSPIRA PERSIMILIS Ulrich 998 



45 Apical side of a specimen from the Trenton group at Hartsville, Tennessee. 



46 and 47 Basal and apertural views of another specimen from the same locality showing 

 the greatly expanded umbilical callosity which distinguishes this species from 

 L. Ifii mi Billings sp. 



