130 
NAUTILUS cariniferus. 
TAB. CCCCLXXXII .—fig. 3 and 4. 
Spec. Char. Discoid, subglobose ; inner whorls 
half exposed in a large umbilicus ; a keel in 
the middle of each side, and two ridges be- 
tween it and the flattened front. 
In general form this resemblesNautilus biangulatus (tab. 
458, j^g. 2.) ; but in addition to the angles which charac- 
terize that, it has on each side of a broad flat front two 
ridges or lesser keels ; in this it approaches N. multica- 
rinatus,but that has a narrow concave area in place of the 
principal keel upon the side. The lesser keels in N. ca- 
riniferus disappear as it advances in growth ; it may possi- 
bly therefore be only a variety of N. biangulatus : the 
specimens with keels are however much larger than the 
specimen figured. All the three species appear to have 
a deep sinus in the lip. 
The great works going on in Cork Harbour have oc- 
casioned an immense display of the fossils of the Black- 
Rock, among which the shell before us is one of the 
less common. 
