CEPHALOPODA 
453 
tile side ; fumiel large and short, closing with an internal valve ; shell, 
° r cuttle-hone, a broad, flat, calcareous substance, with horny edge, 
filled with layers of a spongy substance, supported by pillars. 
The Oetopoda, without tentacles, have eight long arms, united at the 
base by a web; the suckers in two rows, which are sessile; the 
e yes fixed ; shell, two short 
s tiles enclosed in the mantle ; 
tile body united to the head by 
a broad neck-band ; no side- 
fins ; shell internal and rudi- 
mentary in the British species ; 
body oval, warty, and without 
fins, in Octopus; small and 
°blong, arms tapering and web- 
bed, and suckers in a single 
r °w, in Eledone (Fig. 313). 
In his great work, Professor 
ti'vcn proposes to divide the 
Cephalopoda into two groups, Fi&313 ' •W^Ooto P u.™ip*(i««*)- 
^hich he calls JHbranchiaia, characterised by the presence of two 
branchiae, which would bring together all the naked Cephalopoda, includ- 
es Sepia, Suligo, Octopus, 
bot-ssia, and Ommastrephos ; 
a nd Tetrabranchiatc t, having 
b°nr branchiae, to which the 
uutilus , and most of the fos- 
Cephalopods, such as the 
Ammonites, belong. Most of 
the first group are represented 
111 the British seas, but the 
Sec °nd are altogether absent. 
. -file Decapoda are of all 
^ z es. I)r, Grant describes 
be body, or mantle, of 8e~ 
&°k vulgaris, found on V ' i&3U - Octopus macropus (Bisao). 
coast, as measuring about six lines in length, and as much in 
re adth, while the head measures four lines in length, and, from the 
lua guitude of the eyes, must be equal in breadth with the body. In 
