53 
NAUTILUS intermedins. 
TAB. CXXV. 
Spec. Char. Gibbose, umbilicate, concentrically 
striated ; back broad, flattened ; mouth squar- 
ish ; siphuncle nearest the external edge. 
N ot so thick as N. obesus, with flatter sides and a nar- 
rower back ; the septa are also less numerous ; it ap- 
proaches N. truncatus, (tab. 123.) but is thicker, with a 
broader back ; its surface being finely striated, distin- 
guishes it from both. 
From Keynsham. — This and the last might easily be 
confounded with each other ; the siphuncle, however, in 
this, is nearest to the outer part of the shell. From the 
inner part of the front of a whorl that became exposed in 
separating, we find it was longitudinally and finely 
striated. Had not this been discovered, we must have 
depended more upon the siphuncle, which is round and 
not transversely oval. The stone in which this and the 
last figured specimen were imbedded, does not seem to 
differ much. The shells of either appear to have been 
very thin, and are so worn that the numerous and thin 
septa are seen conspicuously exposed. 
How admirable is it that Nature allows us so much 
distinction in specimens that have undergone such vicis- 
situdes, while we are often puzzled with very perfect 
recent ones l It is truly useful, as we the better discri- 
minate their places in the rock and system ; and thus 
will the recent species become more easy to our exercised 
faculties. 
