548 TRANSACTIONS. LIVERPOOL BIOLOGICAL SOCIETY. 
gives off a fine branch to the ink gland at the level where 
the ink duct enters the intestine. It has not, however, 
been followed in ledone. From the posterior edge of the 
gastric ganglion are given off several small nerves to the 
initial part of the intestine and spiral caecum, and also a 
large branching nerve to the postero-ventral wall of the 
stomach (fig. 73, d). 
SENSE ORGANS. 
The general surface of the body of Eledone is sensory, 
the arms in particular forming slender sensory organs. 
There are, in addition, well developed eyes, organs of 
equilibration—the statocysts, and the olfactory organs 
which probably function also as taste organs. 
Tuer Eye. 
Eledone has a pair of prominent eyes, situated one 
on each side of the head (PI. I, fig. 1, #.). As in the ease 
of most Cephalopods, they are sessile. In large specimens 
of #. cirrosa the diameter of the eye is about 25 mm. 
Although it much resembles the vertebrate eye in several 
respects, 1.e., both are vesiculate and both are very 
complex and remarkably perfect in structure, yet there 
are many profound differences. The eye of Eledone has 
no anterior or aqueous chamber, no choroid, and the cells 
of the retina are different from those of the vertebrate 
retina. Again, while the Vertebrate has a cerebral eye, 
that of Eledone originates as an invagination of the 
epidermis, which lJater becomes elaborated into retina, 
iris, &c. Another important point upon which they differ 
is that while in vertebrates the optic nerve penetrates 
the retina and enters the retinal cells from the front, in 
