a OF THE COUNTIES OF NORTHUMBERLAND AND DURHAM. 237 
In Marl-slate; rare. Ferryhill. This species has been found 
only in the above locality. The only fragments known were in 
the possession of the late H. T. M. Witham, Esq. 
Orpur. PLACOIDES, Ag. 
Famity. [cntHyopoRULitHEs, Ag. 
6. GYRACANTHUS, 4g. 
A cast of a spine evidently belonging to a fish of this genus 
was found a few years ago in the quarries of Lower-new-red- 
sandstone, between South Shields and Westoe. It is preserved 
in the Newcastle Museum. 
MOLLUSCA. 
Ciass. CELPHALOPODA, Cuvier. 
OrperR. TETRABRANCHIATA, Owen. 
Famity. Navrinipa, Gray. 
7. NAUTILUS, Linneus. 
1, N. FRInsuesent, Gleinitz. 
Nautilus Frieslebent, Gein., N. Jahrb., p. 637, pl. 11, f. 1. 
Ammonites 2? Sedgw., Geol. Tr. 2nd ser.,1i1., p. 118. 
In Magnesian-limestone; not common. Whitley, Humbleton- 
hill, Tunstall-hill, Silksworth, and Dalton-le-dale. 
The whorls of young individuals are slightly angulated, ite 
they are much rounder in full-grown specimens. The chambers 
are small and numerous, and the siphuncle is close to the ventral 
margin. The dorsal margin is slightly sinuated ; the umbilicus 
moderate, and the surface covered with obscure strie of growth. 
It is not very common, and is generally in fragments when 
found. 
