55 
NAUTILUS excavatus. 
TAB. DXXI X.—fig. 1. 
Spec. Char. Nearly globose, smooth ; sides ex- 
cavated by a very large conical umbilicus. 
The whorls of this Nautilus increase very rapidly : 
they are so wide that they would produce a spherical 
form, were it not for the large umbilicus which occu- 
pies nearly half the diameter of the shell. The front of 
the aperture is arched ; the sides straight, converging 
towards the preceding whorl ; the siphuncle nearly 
central. 
From the collection of the late Mr. G. Humphries ; 
most probably from Dorsetshire. It seems to have been 
taken from the Inferior Oolite. 
NAUTILUS hexagonus. 
TAB. DXXIX.— fig. 2. 
Spec. Char. Short cylindrical ; sides depressed, 
conical; front broad, straight; umbilicus small; 
aperture sagittate, truncated ; siphuncle nearest 
the inner edge of the septum. 
In this species the septa are rather numerous and not 
much curved : its most remarkable character is the 
straightness of the lines that bound a section of it in the 
plane of the aperture, which section being an elongated 
hexagon has suggested the name. 
Far from rare in the Calciferous Grit at Shotover, 
Abingdon, &c. — the specimen figured was from the 
former place. It is in the cabinet of H. H. Goodhall, 
Esq. Sometimes the shell is decayed, when the casts ot 
the cells become loose, and may be separated like those 
of Ammonites Catena, tab. 420, along with which they 
are found. 
