109 
The existence of these shells, in a fossil state, was known to Bec- 
carius and Plancus, who found them in considerable numbers in the 
mountains not far distant from Rimini and Bologna. Plate XI. 
Fig. 2/, is one of these fossil shells, brought from the Appennines, 
in the neighbourhood of Sienna, by Mr. Meade. The matrix is a 
yellowish spathose concretion. 
The reversed variety of this species, or, as it is in general consi- 
dered, the reversed species N. heccarii reversus, is also found in con- 
siderable numbers on the Appennines, along with the former. This 
reversed fossil shell is represented Plate XI. Fig. 28. The opposite 
side of the shell is here represented; but, being of a reversed shell, 
it runs in the same direction as Fig. 2J. 
Among the minute shells which Plancus considered as recent Cormia 
ammonis, were some which he distinguished as being bordered ; since 
many of them, especially those which were whole, possessed a wide 
pellucid margin, which was spread round the whole shell. Whether 
all these shells were naturally thus bordered, and lost this border by 
the violence of the waves ; or whether those which are bordered are of 
a distinct species, he attempts not to determine. De Conch, min. not. 
Cap. iv. Similar shells have been found fossil in the hills of Bologna 
and of Piedmont ; and both the recent and fossil ones, he observes, 
are sometimes found as large as small lupins. App. 1. p. 85. 
One of these fossils, through the kindness of Mr. Meade, is repre- 
sented Plate XI. Fig. 30. It appears to accord very nearly with Nau- 
tilus subarcuatulus, Supp. to Test Brit. Plate XIX. Fig. 1, the sepa- 
rated convoluted portion of which had been taken for N. calcar. 
LXXIII. Spirula. A multilocular shell, partly spiral and partly 
straight, the turns being disposed in a discoidal form, and separate 
from each other ; the last turn being elongated, and continued in a 
straight line. The septa are transverse, regularly concave outwards, 
and pierced with a shelly tube : the opening circular. 
This genus is very properly separated from Nautilus by Lamarck ; 
