gS8 MOLLUSCA. CEPHALOPODA. Nautilus. 
Colour opake brown. Chambers diminishing in size to the mouth, which 
is contracted. Syphon near the distal margin, produced. The partitions are 
represented in Montagu’s figure as tuberculated, though this character is 
not noticed in the description. 
4. S. carlnatula . — Outer margin slightly carinated. Cham- 
bers increasing regularly in size. 
N. oblongus carinatus apertura lineari ovali, Walker^ Test. Min. t. iii 
f. ^2.-^Mont. Test. Brit. 195. 
Colour white, transparent. Chambers seven. The first globose. Montagu 
states, that the drawing of this shell, sent to him by Mr Boys, differs from 
the figure which Walker published, — an occurrence too frequent in the same 
quarter. 
Gen. III. NAUTILUS.-^Sides equal; the last whorl em- 
bracing and concealing the previously formed ones. 
5. N. crlspiis . — Exteriorly carinated. Spaces between the 
partitions crenated. Sides convex. 
Linn. Syst. i. 11G2. Walker.^ Test. Min. t. iii. 65. Munt. Test. Brit. 
187. t. xviii. f 5 — Among old shells and corals — Common. 
Size about of an inch. Chambers in the last whorl about 20; the par- 
titions fiexiious, elevated, canaliculated. Mouth cordate ; the aperture or 
syphon minute, near the proximal edge. In the young shells, the partitions 
are destitute of the gutter, and the margin is more rounded, 
6. N. calcar. — Exteriorly carinated. Spaces between the 
partitions smooth. Sides convex. 
Mont. Test. Brit. 189. t. xv. f. 4. — N. rotatus, Turt. Conch. Diet. 118. — 
On shells and corallines on the English coast. 
Chambers in the last whorl 6 ; the partitions marked by elevated flexuous 
lines, wdiich do not reach, however, to the carmated margin. Mouth semi- 
cordate, clasping. 
7. N. IcEvigatulus . — Exteriorly subcarinated. Mouth with 
a rim. Sides convex. 
N. spiralis geniculis Icevibus, Walker Test. Min. 19. t. iii. f. 67. Mont. 
Test. Brit. 188; Suppt. 75. t. xviii. f. 7-8 — English or Scottish shores. 
Chambers about 10, glossy, smooth ; the partitions marked by subelevated 
flexuous rays. Mouth triangular, with a rim which does not clasp the body 
whorl. Aperture near the distal edge. The mouth seems liable to vary in 
form, as in a specimen w^hieh I found in Zetland, in which it is rounded and 
turned to one side. 
8. N. depressiiliis.-— Depressed^ exteriorly rounded ; the cham- 
bers and partitions nearly even. 
N. spiralis utrinque subumbilicatus geniculis depressis plurimis. Walker, 
Test. Min. 19. t. iii. £ 68.— N. dep. 3Iont. Test. Brit, 190; Suppt. 78. 
t. xviii. f. 9. — English and Scottish shores. 
Chambers about nine in number ; the partitions slightly curved, ending at 
the centre in a pellucid spot. 
9. N. timhilicatuhis.~-Deipi'esiied^ exteriorly rounded ; parti- 
tions sunk, with a subtuberculated elevation in the middle. 
