PLATE XXIII. 



PAGE 



Fig. 15. Ammonites fkateenus. 137 



15 a. Cross section of last volution. 



15 6. Septum. 



Fig. 16. A. Stoliczkanus. 135 



16 a. Front view of the same. 



Fig. 17. Septum of Ancyloceras Rkmondii. 138 



Fig. 18. ? Ancyloceras lineatus. Side view of straight limb. 139 



18 a. Dorsal view of same. 



18 b. Cross section of same. 



18 c. Septum. 



