82 UNIVALVES— NAUTILUS. 
The Nautili. differ exceedingly in size; some are so 
small that they can only be defined by the microscope, 
while others are nearly a foot in diameter. 
The N. scrobiculatus is the most rare species of this 
genus 
Some species of the Nautilus are found adhering to co- 
ral rocks, particularly the N. siphunculus, which is often 
brought from the coral reefs on the Sicilian shores. 
The American and Indian Oceans, as well as the Me- 
diterranean, Adriatic, and Red Seas, produce species of 
Nautili; but the greater number are found on the Eu- 
ropean and British coasts. The species from the last 
mentioned locality are minute. 
This and the preceding genus, from a similarity in 
form, were originally included under the same generic 
name NavztXoe, (sailor),so called by the early naturalists, 
from the nautical skill which the animal of the Argo- 
nauta was supposed to exert in directing its fragile bark. 
The great difference in internal structure induced sub. 
sequent conchologists to separate the genera. 
In the following enumeration of the species of th 
genus, we have omitted the names of those which w 
have not found figured in any author. They are, wit 
few exceptions, microscopic shells. 
Diviston I.—Spiral, with contiguous whorls. 
Scientific Name. Locality. Common Name. 
Pompilius ---.-.- Africa, Amboyna, China, 
India -----++....-..--, Gt. chambered N 
Scrobiculatus-.-. New Guinea ---++-++.+- Sunken spiredo «+ 
Lacustris:.-+--- Kent, Denmark --...>-- Lake--..-- do -: 
