io7 
not to be the cast of a chamber, but a disengaged septum ; some of 
which I have, I believe, from Shepey; and others, which I have 
reason to suppose to be foreign. 
Plate XL Fig. 25, is a minute fossil shell found on the Appennines, 
near to Sienna, by Thomas Meade, Esq. of Chatley Lodge, near Bath, 
whose kindness I shall have repeated occasion to acknowledge. This 
shell appears to be N. crispus, Linn, having lateral spires, with about 
twenty flexuous crenated joints in the exterior whirl, marked by ele- 
vated striae ; outer edge carinated ; inferior volutions occult ; aper- 
ture clasping the body ; semicordate ; furnished with a small perfo- 
ration or syphon. Testae. Britan, p. 187- Plancus observes, that 
none of these beautiful fossils are found on the yellow sand of Bo- 
logna ; but that they are very abundant in the sand of the mountain 
Covignani, in Rimini. 
To the kindness of the same gentleman I am indebted for the op- 
portunity of laying before you the minute fossil nautilus, Plate XI. 
Fig. 26, which is perhaps one of the species alluded to by Colonel 
Montague, as a very minute non-descript species, found with the other 
minute Sienna fossil shells. This is spiral : the inner turns concealed ; 
the outward turn is wide toward the middle of the shell, where it is 
umbilicated ; but very narrow at the back, and is formed of about 
fifteen chambers. I have but one specimen of this fossil, and am 
unable to discover any thing respecting its siphuncle. This shell is 
more minute than the preceding fossil, and in its general form very 
much resembles a reduced N. pompilius. 
Considering the genus Nautilus of Linnasus as too comprehensive, 
and that Nautilus should contain only those spiral multilocular shells 
whose inner turns are concealed, and whose siphuncle is obvious ; and 
that Ammonites should include those whose turns are apparent on both 
sides, but whose siphuncle is concealed ; no genus is left for the re- 
ception of those minute shells which were discovered by Beccarius and 
Plancus, in which the characters of Nautilus and Ammonites are 
