254 ZOOLOGY. 
rim inside. Two of the ten arms arise from the under side 
of the head ; they are twice the length of the eight others, 
and oval at the end. On each side of the head behind the 
tentacles are the remarkably large eyes, which, though usual- 
ly said to be more like the vertebrate eye than those of any 
other invertebrate, are really 
constructed fundamentally on 
the same plan as the eye of 
the snail; differing in several 
important respects from that 
of a Vertebrate, the resem- 
blances between the two being 
superficial, while the struc- 
ture of the eyes of mollusks is 
quite unlike that of Crusta- 
ceans, insects or Vertebrates. 
The mantle loosely invests 
the front of the body next to 
the head, so that the water 
¥| passes in around the neck in 
de order to bathe the gills, which 
ae{/ are quite free from the visce- 
@S ralmass. The mantle is beau- 
I tifully colored and spotted, 
the change of color being dne 
to the change in form of the 
pigment masses or chromato- 
phores, which are under the 
influence of the peripheral 
nerves. 
The mantle is supported by 
7 r ‘ “cc ” 
ort ee on Pe acport oe 
tending from the upper side of the anterior edge of the 
mantle to the end of the body. In the Sepia of the Medi- 
terranean Sea this is thick, formed of limestone, and is 
called the ‘‘ cuttle-fish bone.” 
The organs of digestion consist of a mouth, pharynx, 
cesophagus, stomach and intestine. The mouth is situated 
