123 
EAST. ZOOL. GAL.] NATURAL HISTORY. 
most, or walk and run on their heads with the end of 
their body on high. 
The family of Sea-spiders ( Octopodidce ) have a purse¬ 
like body, without any fins, only eight sessile arms, and 
no shell. The Ocythoce , which have the ends of the two 
dorsal arms webbed, take possession of the Argonaut's 
shell, when they are about to lay their eggs. The Philo - 
nexi, which have no eyelids and free arms, live on the 
ocean, while the Octopodes and Eledonce , which live on 
the coast, have distinct eyelids. 
The family of Cuttle-fish ( Sepiadce ) have an elongate 
body with a fin on each side; they have, besides the eight 
arms of the former family, two longer arms, cylindrical at 
the base and enlarged and furnished with suckers at the 
end, which are not developed until some time after they 
are hatched. They have a cartilaginous or calcareous in¬ 
ternal dorsal plate. 
From the imperfect specimens of the animals of the ge¬ 
nus Spirilla which have been seen, and from the very 
small size of the terminal chamber, the tenuity of the 
structure, and the colour of the shell, there is every rea¬ 
son to believe that it will form a family of this order ; 
and if this should be the case, it is very probable, as the 
shells have the same texture, an equally small terminal 
chamber, and a very contracted mouth, that the fossil 
Ammonites , Scaphites , and other allied genera, will also 
be referrible to this order, or to a new one charac¬ 
terised by the developement of the shell, and regular 
syphoned septa. Their shells are to be distinguished 
from Spirula by the edge of the chamber being sinuated 
and the syphon placed near the dorsal surface. 
The- Nautilophora have an oblong body inclosed in 
the cavity of the last whorl of a chambered shell, which 
nas a tubular syphon passing through each of the cham¬ 
bers ; their eyes are slightly pedicelled, and they have 
eight arms, with numerous divisions, furnished with short 
tubular retractile tentacles and four gills. 
The family of NautiUdce have two series of very numer¬ 
ous tentacles, and a large fleshy appendage on the head, 
serving the animal as a foot for locomotion ; the shell is 
exterior, with simple concave septa between the chambers, 
and the syphon in the centre or near the inner edge. 
g 2 
