202 GENESIS OF THE ARIETID. 
) depressed form of the whorl, and the coarse pile: which cross the abdomen have 
a similar broad, flattened aspect. The siphonal saddle, according to Wright's 
figures, Plate LXII. A, seems to have suffered considerable alteration from what 
it is in the typical form of obtusum. The lobes and saddles of the Bempflingen 
specimens have the regular differences of one half to one third in the lobes, and 
the abdomen is unusually broad. 
There is a specimen of variety D, from Lyme Regis, in which for a short 
space the keel has been pressed inward and the sides ruptured. While on the 
recovery from this injury the abdomen retained a flattened aspect, it is about as 
broad as that of some forms of sagitéarium, and otherwise similar. Narrow folds 
and furrows are noticeable crossing the abdomen, which correspond to similar 
small folds and furrows on the sides. The effect of the rupture is otherwise 
noticeable in the temporary absence of the pile and the greater intervals be- 
tween the next two pairs of sutures. This example shows that there may be 
a tendency to vary in the direction of Microceras, which is produced in some 
specimens by disease, and in others by wounds. Such characteristics were not 
observed in the later stages of diseased specimens. They probably disappeared 
in course of growth, just as the similar characteristics of the young of Cor. 
Sauzeanum were suppressed in the adult stages. 
The forms of this species may be divided into several varieties, according to 
the adult characteristics, and the slower or quicker development of the keel, 
| channels, and form. 
Var. B. 
This has flattened sides, pile not very prominent, but running nearly to the 
base of the keel, and the channels are very narrow as well as shallow. 
Var. C. 
This is the normal Zurneri of Zieten, and has the pile reaching nearly to the 
base of the keel in the nealogic stages, and perhaps in the adult. In all other 
characteristics, even in the prominence of the pile, it agrees with variety D. 
Var. D. 
Plate IX. Fig. 1. 
This is the typical form, and has well rounded, gibbous sides, prominent pile, 
broad abdomen, broad shallow channels, and a depressed keel. 
Van. EB. 
Plate VIII. Fig. 4-8. 
| This is similar, but has deeper channels and a keel more prominent, narrower 
i and more convergent sides in the adult, showing some resemblance to Asé. ; 
i Turneri, Hauer’s specimen of Amm. stellaris figured in “ Nordéstlichen Alpen” 
belongs to this variety, and is not identical with the true stedlare. 
The pile may be gradually introduced by a series of plain folds, or by tuber- 
cular folds, Plate VIII. Fig. 4, 5. The whorl is smooth in specimens having the 
