PLATE 48. 



Fig. 1, 2, 3, 4. Endoceras proteiporme. {^^g- 213.) 



•1. A frajsfment of a large specimen, composed of twenty or more chambers, one side of whicli is worn down, 

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



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



4 e. 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 tlie parent sliell. 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. 



2. A similar tube, free from stria;, and like the others. This tube has been broken at a, b, e ; 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 throughout its entire length, and furnished with an cxcentric siphuncle, 

 which is distinctly represented in the section a. 



1. A separate embryo tube, nearly perfect, and showing some inequalities near the base, apparently from con- 

 tact with the inner side of the siphuncle. 



