98 
NAUTILOIDEA. 
flattened sides, and nearly direct across the back. They are closely 
placed, very much as in the Carboniferous species.” (Salter.) 
Horizon. Uncertain. 
Locality. Guuesgunga ; in a boulder. 
Represented in the Collectiou by the type specimen described and 
figured by J. W. Salter. 
Subgeiius PHACOCERAS, Hyatt b 
{Nautili Lenticulares, de Koninck, 1878“.) 
This subgenus differs from Discitcs in its lenticular, highly com- 
pressed form and acute periphery. The young arc longitudinally 
Fig. 12. 
Discites {Phacoceras) oxystomus. — a, lateral view of an imperfect specimen, 
showing the septate part of the shell and a portion of the body-chamber ; 
the latter begins at the deep notch on the right of the figure : b, front view, 
sli owing the lenticular form of the shell and the extremely sharp periphery. 
Drawn from a specimen in the Collection. About two-thirds of the 
natural size. 
dged like Discites. The whorls are deeply embracing, and there 
is a very strongly impressed zone of involution upon the dorsal 
side. Type, Nautilus o.vystomus, Phillips. 
Carboniferous. 
^ Proc. Boston Soc. Nat. Hist. 1883, vol. xxii. p. 292. 
^ Faune du Calcaire Carbohifere de la Belgique (Aunales du Mus. Roy. 
d’Hist. Nat. de Belgique, tom. ii.), pt. i. p. 90. 
