120 GREY CHALK MARL. 



indentations, with several minute sinuosities. The situation of the 

 siphunculus is unknown, but appears to have been on the internal margin. 



The specimens consist of indurated marlaceous casts, occasionally pos- 

 sessing portions of the shell. The inner volutions are often filled with 

 svilphuret of iron, and sometimes with calcareous spar. In almost every 

 instance, the spire is more or less oblique, and otherwise distorted by com- 

 pression : the variations of shape observable in the specimens delineated, 

 have evidently been produced by this cause. 



Tab. xxii. fig. 3, a dorsal, and fig. 4, a lateral view of a Scaphite from 

 Hamsey, flattened by compression. 



Fig. 9, exhibits the obliquity of the spire : a straight specimen, in my 

 possession, proves that this appearance is the effect of accident. 



Fig. 11, exhibits the usual characters of the species; the aperture is 

 l)roken off. 



Fig. IS, a specimen from Ranscombe, remarkably distorted. 



Figs. 14, 15, different views of a pyritous cast of the inner volution : 

 the dark spot in the centre of fig. 14 shews the supposed situation of 

 the siphunculus. 



Fig. 16, is a longitudinal section; the inner chamber is filled with dark 

 brown sulphuret of iron. 



LocaUties. Hamsey, Eodmill, Brighton. 

 36. Scaphites costatus. Tab. xxii. figs. 8, 12. 



Volutions convex, laterally compressed, transversely striated, inner 

 whorls concealed, inserted; strias furcate, numerous, embracing the ambit: 

 sides of the outer volutions smooth, with eight or ten distant, oblique, no- 

 dular projections ; dorsum broad, convex. 



This is a less delicate shell than the former; its length is 1 inch, width 

 0*8 inch ; thickness of the back 0-6 inch. It is distinguished from S. 

 striatus by the nodular projections on the sides of the external volutions. 

 These proceed from the centre, and diverge into numerous striae, which 

 encircle the ambit. The back is broad, and the projecting terminations 

 of the striae give its edges an undulated appearance. The aperture is 

 oblong, and fronts the spiral part. 



