212 
NAUTILOIDEA. 
figured specimens (which are both casts) had a closed umbilicus, 
because if the shell were present it would entirely fill up the cavity 
seen in the cast. Another specimen (cut and polished and also 
numbered 43854) is also labelled by Sowerby “ Nautilus lineatu^^ 
Fig. 41. 
Nautilus lineat us.— a, lateral view, showing the closed umbilicus, and parts of 
the septa where the test is broken away ; h, front view, sliowing the posi- 
tion of the siphuncle and the compressed form of the shell. Drawn from 
a specimen in the British Museum (Iso. 43854 a), “Sowerby Collection.” 
A little less than one half natural size. 
M. C.,” but it differs from his figured types in more than one parti- 
cular, viz. in its more flexuous and less numerous septa, and in the 
siphuncle, which, instead of being near the centre, as in the type 
(lower figure of Sowerby’s plate), is above. To this form we have 
therefore given a new name — Nautilus pseudolineatus. 
Nautilus lineatus must now be restricted to shells of a somewhat 
robust habit of growth, with flattened sides and broad flattened 
periphery, closed umbilicus, numerous, very slightly flexuous septa, 
and a nearly central siphuncle. It may be added that the shell 
had a perfectly smooth surface. 
“ The name lineatus^ which was clearly intended by its author to 
have reference to the faint ridge seen upon casts along the median 
line of the periphery, has apparently misled many palaeontologists, 
for we have seen in collections various Jurassic Nautili labelled 
‘ lineatus ’ which certainly belonged to more than one species. In 
