﻿BRITISH FOSSIL CEPHALOPODA. 



Plate II. 



Fig. 



1. Nautilus pompilius. — A vertical section through the inner and outer shell, and 



a septum, a, the outer, b, the inner layer of the outer side of the shell; 

 c, the black deposit made by the succeeding whorl ; d, the outer, e, the inner 

 layer of the inner side of the succeeding whorl ; /, the thin lining of the 

 shell ; g, the deposit in the corners of the septa ; h, the septa. ( x 15.) 



2. A fragment showing, a, the small dorsal lobes ; b, the furrow leading from 



one septum to the next ; c, the septa where the dorsal lobes have died away. 



3. Front view of half the body-chamber, showing the vascular marks on the con- 



cave surface. 



4. Section of the earliest chambers, a, the cicatrix ; 6, its thickened outer layer ; 



c, the inner layer overlapping that of the shell ; d, the black deposit of the 

 succeeding whorl ; e, the first septum resting against the end of the shell ; 

 /, the long neck of the second septum on the convex side ; g, the inner, 

 h, the outer layer of the siphuncle. ( x 18.) 



5. Front view of the commencement, showing, a, the cicatrix ; b, the longitudinal 



lines forming a network with the lines of growth (after Hyatt). 



6. Horizontal section of the outer layer of the shell, a, the darker coloured portion. 



(x 135.) 



7. Horizontal section of the inner layer, showing the outcrop of the fine laminae, 



disturbed at a ; also the small lacunas. ( x 135.) 



8. Another similar section from the concave side of the succeeding whorl, showing 



the larger radiating lacunae, (x 135.) 



