PLATE XXXVIII 
Fig. 1. Monocyrtoceras lentidilatatiim Foerste. Ventral view, ex- 
posing one segment of the siphuncle at the base. Same specimen as Plate 
XXXVII, fig. 1. 
Fig, 2. Elrodoceras indianense (Miller). Lateral view, with ventral 
side on right; exposing 4 segments of the siphuncle. Same specimen as 
Plate XXXVII, fig. 2. 
Fig. 3. Elrodoceras cf, indianense (Miller). Lateral view of part of 
cast of interior of siphuncle, showing relative size of passage of siphuncle 
through septum at top of specimen. From Joliet, Illinois, in the Niagaran. 
No. 22916, in Walker Museum, at University of Chicago. 
Fig, 4. Actinoceras sp. Lateral view of cast of interior of siphuncle, 
showing nature of deposits here. From Joliet, Illinois, in the Niagaran. 
Also numbered 22916, in Walker Museum, but belonging to a different 
species from the preceding. 
