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LXXXVI. Lenticulina. A sublenticular, multilocular, spiral 
univalve ; the external margin of the turns being complicated, the 
septa reaching to the centre on each side : the septa entire, curved, 
and standing out, on the upper and under surface, like rays. The 
aperture narrow, and projecting beyond the penultimate turn. 
These shells are distinguishe d by Lamarck from those of Nautilus 
by their having no syphon ; and from those of Discorbis and Iiotalites, 
by the septa reaching to the centre on each side. He states, that the 
recent shell has been found in the sea, near Teneriffe, at the depth 
of a hundred and twenty-five feet. Three species are found fossil in 
the environs of Paris : X. planulata, X. variolaria, and X. rotulata. 
The last of these I have represented from Lamarck, Plate XI. Fig. 4, 
being entirely unacquainted with this genus. 
LXXXVII. Lituola. A multilocular univalve, partly spiral, the 
last turn being straight at the end : the chambers irregular : plain 
transverse septa, the last having several openings. 
The chambers of this shell appear to be very irregularly disposed, 
and the orifices in the last septum are generally from three to six ; 
but the other septa do not appear to be pierced by any siphunculus. 
Lamarck describes two species, both fossil, not knowing of their 
existence in a recent state. Plate XI. Fig. 5, is a representation of 
Lituolites nautiloidea. Fig. 6, is X. cliff jrmis ; and Fig. 7? is the 
same shell, rubbed down, to show the internal structure. 
I have suspected the former of these shells to be, perhaps, N. semi- 
lituus, or suharcuatulus, and the latter to be N. carinatulus, Fig. 73, 
of Walker ; but there is no agreement in the openings. 
LXXXYIII. Spirolina. A multilocular univalve, in part spirally 
convoluted : the turns contiguous, the latter ones straight : the septa 
transverse, perforated by a tube. 
These minute shells are so alike in their general form to those of the 
genus Spirula, that Lamarck, who has discovered several species and 
VOL. III. 
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