NATURAL HISTORY. 
39 
gallery.] 
for sails, and its slender arms as oars, from whence Pope gave his well 
known lines, 
“ Learn from the little Nautilus to sail, 
Spread the thin oar and catch the driving gale,” 
proves to be a fiction. The dilated arms are used by the animal to 
clasp the shell and keep it on the body, when it passes through the 
water, like other cuttle fish, with the broad part of the body forwards. 
The flat orbicular shell of the Chinese umbrella ( Umbrella ), and the 
horny thin silvery shells found under the skin on the backs of Pleuro - 
branchus and Berthella. The Limpets {Patella). Scaly Chitons 
{Chitons). Spiny Chiton ( Acanthopleura ). Leathery Chiton (To- 
nichia). Fasciculated Chiton ( Acanthochetes ). Chitonella, or sea 
caterpillars, and the Amiculce , or shelless chitons. 
Tables 24—30. The various genera of Land Shells, as the shelly 
plates which are found under the skin of the slugs and the different kinds 
of snails or Helices: as the Streptaxis, which has the axis bent on one 
side, as if the shell was crushed. The Grecian lamp, (Helix Anas - 
toma,) which has the mouth turned up towards the whorls on the upper 
surface of the shell. The Proserpina , which has the cavity of the shell 
furnished with large continuous folds. 
Tables 27—29. Land Shells continued: as the different kinds of 
JBulimi; the puppets (Pupa); the closed shell {Clausilia), which 
has a shelly valve that closes the mouth of the shell, placed behind the 
plait on the pillar, and the Achatince. Many of these shells deposit a 
large egg covered with a hard shell, like the eggs of birds. The eggs of 
different kinds are in the Case. 
Table 29, 30. The Fresh-water Shells, as the different genera allied 
to Auricula , amongst which is the Carychium , the most minute of the 
British land shells; and the different kind of pond snails ( Limneus ), 
coil shells ( Planorbis ), and fresh-water limpets {Ancylus). The 
Amphibolce , from Australia. The Siphonariee, which so much resemble 
the limpets; and lastly, the various kinds of Cyclostomce and Helicince. 
Tables 31—45. The Bivalve Shells, 
Which are under arrangement into tribes. 
Table 46. The lamp shell ( Terebratula ); Duck muscles ( Lin¬ 
gula) ; the Cranice and JDiscince, the upper valves of which have been 
mistaken by some authors for limpets; the bones of cuttle fish 
( Sepia ); the cartilaginous lances of sea leaves ( Loligo ), sometimes 
called sea pens. The fossil JBelemnites , which are supposed to be similar 
to the small horny process at the end of the cuttle fish bone. The 
crozier shell (Spirula), and the different kinds of Ammonites and 
Nautili . 
JOHN EDWARD GRAY. 
Oct. 26, 1847. 
