PLATE 47. 



Fig. 1, 2. 274. 6. Endoceras proteiforme, var. tenuirtriatum. (Pag. 209.) 



1 a. A small and slendei- specimen of this species. 



1 A. A portion of the surface enlarged, showing the cancellated lines. 



2 a. This specimen presents very similar surface markings, and cannot be distinguished from the last, though 



the transverse striffi are less prominent. The specimen consists of a double or triple tube; the outer one 



2 b showing externally marks of septa, which are distant about one-lburth the diameter. The shell is 



exfoliated, and the surface markings are unl;nown. 

 2 e. An enlarged portion of the surface : the longitudinal stria; are too strong in the figure. 

 2 d. A small portion still farther magnified, showing the proportionate size of the transverse and longitudinal 



strise. 



2 e. Transverse section of the specimen 2 a, showing the proportional diameters of the two, and the section 



of a still smaller tube within 2 a. 



Fig. 3. 269. 22. Orthoceras juncetjm. (Pag. 204.) 



.3 a. A fragment deniided of the shell, showing a part of the outer chamber, and septate \>ortion of the tube. 



3 b. A smaller specimen, showing the marks of septa which appear to be slightly oblique. 

 '■i c. A small fragment, showing the convexity of a single septum. 



'3 d. A section of the last, showing the central position of the siphuncle. 



i e. A small fragment, showing the closer approximation of the septa near the outer chamber. 



3f. A small fragment, preserving the shell and the striated surface. 



Fig. 4. 276. 8. Endoceras proteiforme, var. lineolatum. (Pag. 211.) 



1 a. A fragment from the apex of one of these tubes, which is septate as in the larger specimens. 

 A b. A transverse section. 



4 c. A fragment which is annulated near the apex, and septate to the extreme point. 

 '1 d. Section near the apex. 



4 c. A fragment of a similar young shell, where the lamellose stris have become vesicular, giving a rough 

 scaly appearance to the surface. 



