178 
bend over the aperture, as seen in figs. 21 and 22. A like 
form of mouth-border is seen in the shells of Stephan. Sauzei 
and Stephan. linguiferum, and a still more marked variation of 
the lateral lappets is found in Stephan. Gervillii, Stephan. 
Brongniartum, all derived from the Humphriesanum zone of the 
Inferior Oolite, and Stephan. Bullatum, from the Great Oolite. 
In Cosmoceras the sides are often highly ornamented with ° 
ribs and tubercles, which bespeak a corresponding development 
in the mouth-border of the shell. In Cosmoceras Jason (fig. 23), 
the lateral processes are very long, equalling two-thirds the 
diameter of the last whorl. Many years ago a large number of 
this species was collected from the Oxford Clay, near Chippenham, 
in a very perfect state of preservation, with the body-chamber 
and mouth-border complete. In other species of this group I 
have not been fortunate in finding the termination of the shell. 
Fic. 23.—Cosmoceras Jason, Fic. 24.—Hoplites mammillaris, 
Reinecke, Schloth. 
Fig. 25.—Hoplites mammillaris, Tid aa a par 
Schloth. TG. 26. vaaios Martini, 
