230 
DESCRIPTION OF THE FOSSILS. 
B. acutum. Sow, PL XVI. fig. 11, 21. Bolland ; Northumberland ; 
Kildare. 
Elongate, volutions convex, smooth ; delicately striated. 
B. curvilineum. Ph. PL XVII. fig. 13, 22, 23. Bolland. 
Elongate, volutions very broad, smooth, very obliquely striated. (Young, fig. 22, 
marked with subsutural lines.) 
B. rectilineum. Ph. PL XVI. fig. 10. Bolland. 
Oval, tumid below, smooth, striae direct ; colour stripes flexuous. (Possibly 
var. of B. imbricatum.) 
B. sigmilineum. Ph. PL XVI. fig. 12. Bolland; Kildare. 
Elongate, volutions very convex : striae sigmoidal. (Compare with B, acutum.) 
B. vittatum. Ph. Pl. XVI. fig. 14. Bolland. 
Elongate, volutions very convex, with one broad flat mesial band : aperture oval. 
B. globulare. Ph. Pl. XVI. fig. 15. Bolland. 
Subglobular, whorls very convex ; inconspicuous spiral striae. 
B. amp ullarioideum . Ph, Otterburn ; Northumberland. 
Ovato-conical, spire attenuated, very acute, the body whorl tumid, concave at the 
suture. 
Rostellaria angulata. Ph. Pl. XVI. fig. 16. Bolland, 
Whorls angular, the upper ones tricarinate. 
CEPHALOPODA MONOTHALAMIA, 
Bellerophon. An extinct genus, unknown in the superior strata. 
B. tangentialis. Ph, Pl. XVII. fig. 6, 7 > and 14. Bolland ; Queen’s 
County. 
Cylindri co-glob ose, with a largely rounded umbilicus ; aperture greatly expanded ; 
back broad with a sharp and narrow keel, sending off straight ridges and furrows which 
are perpendicular to the keel and form tangents to the inner margin. 
B. costatus. Sow Pl. XVII. fig. 15. Craven ; Bolland. 
Subglobose, umbilicus small, rounded, dorsal band broad ; stria; sharp, arched 
from the umbilicus to a deep V-shaped dorsal sinus. I have attempted a restoration of 
the species from a fine specimen in the Yorkshire Museum. The inner part of the 
shell covers with its smooth expansion the ridges of the dorsal face. 
B. hiulcus. Sow. Pl. XVII. fig. 5 . Bolland ; Derbyshire. 
Differs from the last chiefly by its finer striae, and greater width. 
B. tenuifascia. Sow. Pl. XVII. fig. 9, 10. Bolland. 
Form nearly as the last ; umbilicus small, striae fine : keel narrow and sharp. 
