PLATE 53. 
Fig. 1. 281. 13. ENpocERAS MAGNIVENTRUM. (Pag. 218.) 
1 a. A fragment, showing several of the chambers, with the large siphunle projecting above. 
1b. An artificial longitudinal section, showing the proportional diameterof the siphuncle and shell, as well 
as the extreme convexity of the septa, which are correctly represeited as somewhat irregular in this 
respect. 
1c. A transverse section of the larger extremity, which is worn off obliquey, At dd the outer line indicates 
the edge of the siphuncle ; the inner one being perhaps an exfoliatio. from the same, but too obscure 
to determine its character. At e, the embryo tube, with a young shell.is clearly distinguishable within 
the siphuncle. The position of the same is shown in the longitudinalsection, which slightly cuts its 
outer edge. 
Fig. 2. ENDOCERAS PROTEIFORME. (Pag. 213.) 
A large fragment of this species, in which the embryo tube is preserved, while tie surrounding shell has been 
partially removed. 
