vol. xx. (3) THE LIASSIC ROCKS OF ENGLAND 
245 
ON NAUTILUS PSEUDOTRUNCATUS N. SP„ FROM 
THE LIASSIC ROCKS OF ENGLAND. 
BY 
The late G. C. CRICK, F.G.S. 
Nautilus pseudotruncatus, sp. nov. 
Specific Characters . — Shell composed of a few inflated, 
rapidly-expanding, squarish whorls ; greatest thickness at a 
short distance from the umbilical margin a little more than 
two-thirds of the diameter of the shell ; height of outer whorl 
a little more than one-half of the diameter of the shell. Whorls 
few ; inclusion almost complete ; umbilicus deep, with nearly 
vertical, rather convex sides and rounded margin, about one- 
sixth of the diameter of the shell in width. Whorl trapezoidal 
in transverse section, about one-third wider than high ; in- 
dented to a little more than one-sixth of its height by the 
preceding whorl ; periphery flattened, broad, a little more than 
one-half of the corresponding diameter of the shell in width, 
with subangular margins ; sides flattened, fairly well defined 
both from the peripheral area and from the umbilical zone ; 
umbilical margin subangular ; umbilical zone feebly convex, 
almost vertical to the plane of symmetry of the shell. Body 
chamber occupying at least three-eighths of the outer whorl ; 
aperture not seen, but, judging from the growth-lines, its 
margin showed a broad, rather deep hyponomic sinus on the 
periphery, a very shallow sinus on the lateral area, and projected 
considerably forward at the umbilical margin. Chambers 
moderately deep, about one-half of the corresponding height 1 
of the whorl in depth ; their number to a whorl not seen ; 
septa feebly concave ; suture-line with a broad shallow sinus 
1 That is from the umbilical suture to the periphery. 
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