60 
EXPLANATION OF 1>LATES 39. 40. 
A portion of the outer shell is preserved at c. and im- 
pressions of the fluted interior of the shell, which has fallen 
off, are visible at d. (Original.) 
Plate 39. V. I. p. 348. Note. 
This Plate presents a longitudinal view of the same 
fossil, of which a side view is given in the last figure. 
The same transverse plates, that approximate so closely 
beneath the sides of the shell, where it is flat and feeble, 
(PI. 38.) are distant from each other along the dorsal por- 
tion, which from its convex form is strong. 
The Siphuncle is preserved in its proper dorsal place 
at d. 
The elevations and depressions of the transverse plate 
in front of this figure exemplify the theory of Von Buch, 
respecting the use of the Lobes and Saddles formed by the 
undulations of its outer margin. See V. I. p. 353, and 
Note. (Original.) 
Plate 40. V. I. p. 360. Note. 
Fig. 1. Ammonites Henslowi (Goniatites), from Tran- 
sition lime-stone in the Isle of Man. 
The Lobes are simple, and without foliations; 
their form resembles that of the slipper-shaped lobe 
of the Nautilus Ziczac, and Nautilus Svpho. See 
PI. 43. 
The lobes D. L. 1. V. are pointed inwards, and 
the intermediate Saddles S. d. S. L. S. V. are 
rounded outwards; according to the type of Ammo- 
nites. (Original.) 
Fig. 2. Ammonites striatus (Goniatites), from the Coal 
Shale of Lough Allen in Connaught, having its 
lobes and saddles disposed in the same directions 
as in Fig. 3, tlie delicate longitudinal strim and 
