PLATE 48. 



Fig. 1, 2, 3, 4. Endoceras proteiforme. (Pag. 213.) 



4. A fragment of a large specimen, composed ot" twenty or more chambers, one sitle of \vliich is worn down, 

 exposing the sipliuncle, which contains the embryo tube, within which is a young shell a. 



4 b, b. The larger or embryo tube, which is broken at tlie lower extremity. 



4 c. The siphuncle, the space surrounding the tube being filled with calcareous spar. This specimen shows, 

 in a very satisfactory manner, the position of these tubes within the parent shell. A small portion of the 

 upper part only of the embryo tube is preserved. 



.3. An embryo tube with a longitudinal section on one side, showing a slender septate tube within, whicli is 

 nearly destroyed by weathering. 



^. A similar tube, free from striie, and like the others. This tube has been broken at a, b, c ; and the trans- 

 verse sections a, b, c, at the bottom of the plate, represent its appearance. The outer tube contains an 

 inner one, which is septate througliont its entire length, and fiu-nislicd wilii an excentric sijjhuncle, 

 whicli is distinctly i-epresented in the section a. 



I. A separate embryo tube, nearly perfect, and showing some ineiiualities near the l)ase, apparently from con- 

 tact with the inner side of the siphuncle. 



