PLATE 84. 



Fig. 1. 369. 4. Cyrtolites oknatus. (Pag. 308.) 



1 a. Lateral view of a cast of this species. 1 b. Profile of tlic same, looking into the aperture. 



1 c. Another specimen (a cast), where the volutions are contiguous. 



I d. A specimen preserving the shell, from which the finer stria: are removed. 



1 e. A portion of the surface of the shell, showing the sculpture. 1 /. Part of the same magnified, 



I g. A transverse section of the shell. 



Fig. 2. 



249. 1. Thocholites ammonius. 



(Pag. 309.) 



2 a. A small specimen, partially preserving the shell in some parts, and showing the septa in others. 

 2 6. An enlarged portion of the surface, which is partially exfoliated, and slightly different from similar mag- 

 ni^ed parts of those in the Trenton limestone, where the shell is well preserved. 



2 e. Mould of a large specimen in the black slate. 



Fig. 3. 370. 2. Tkochoutes planorbifoemis. (Pag. 310.) 



3 a. Figure of a specimen nearly entire. 3 b. Dorsal view of the same. 



3 c. Ventral view of a fragment, preserving part of the two outer volutions, showing the concaye ventral side, 



and the position of the siphuncle. 

 3 c*. Section of the outer volution. 3 d. A portion of the surface magnified. 



3 e. A specimen crushed in a vertical direction, a part of the outer volution retaining its form. 

 3/. Dorsal view of the same, showing the slightly arching septa upon the dorsal line, and a part of the outer 



chamber. 



1 ' 



