PLATE XXX. 



Zone of Aegoceras armatum. 



Fig. 1. Aegoceras Leckenbyi, Wright. Lateral view, natural size. Leekenby collec- 

 tion, now in the Woodwardian Museum, 

 Cambridge. 



2. — — Siphonal area, showing the ribbing and 



the smallness of the tubercles. 



3. — Front view of the same shell. 



4. — — Another example in the same collection. 



5. — — — Front view, showing the lobes. 



6. — — — Siphonal area, showing the ribbing and 



convexity of this area. 



7. — — — Accurate tracing of a portion of the lobe- 



line, showing the narrowness of the siphonal 

 lobe and the magnitude and complication of 

 the principal lateral lobes. 



