PLATE XV. 



Orthoceras laterals, Phillips. (Page 144.) 

 Fig. 



1. The largest specimen known. Wolborough. Vicary Collection. 



2. Small specimen showing the acuminate apex, which is not quite perfect ; 2 a, 



diagram of section ; 2 b, portion of surface enlarged and partially restored. 

 Wolborough. Vicary Collection. 



3. Another specimen showing the septa and the wall of a chamber. Wolborough. 



Museum of Practical Geology. 



4. Diagram of section of another specimen showing position of siphuncle. Wol- 



borough. Museum of Practical Geology. 



5. Another specimen showing the septa. Wolborough. Museum of Practical 



Geology. 



Orthoceras cf. 0. tceniale, Barr. (Page 148.) 



G. Specimen wanting external shell, showing the septa. 6 a, diagram of section 

 showing the siphuncle. Wolborough. Vicary Collection. 



Orthoceras speciosum, Milnster. (Page 149.) 



7. Rather doubtful specimen with very oblique septa. Wolborough. Vicary 



Collection. 



8. Phillips' original specimen (204 a) ; 8 a, diagram of section. Wolborough. 



Museum of Practical Geology. 



9. Large specimen with rather deep chambers, wanting the shell, and showing 



a carina upon its surface. Wolborough. Vicary Collection. 



10. Specimen partially retaining the external shell, though much worn. The septa, 



and the shape of the siphuncle are seen at the top. The cylindrical appear- 

 ance is accidental, being caused by the wearing away of the walls above, 

 and by a breakage below. Wolborough. Vicary Collection. 



Orthoceras Champernowni, n. sp. (Page 142.) 



11. Large specimen of the body-portion of the shell retaining the surface, but with 



no remains of ornament. 11a, diagram of section showing siphuncle. 

 Wolborough. Museum of Practical Geology. 



12. Polished longitudinal section, showing the very narrow septa, and the position 



and beaded character of the siphuncle. Lummaton. Champernowne 

 Collection. 



