- 158 Transactions.—Z4oology. 
ciliare. The lens is surrounded by a deep groove, so as to form practically 
two lenses, the outer one being the smaller, the inner the larger and more 
convex. It is in the groove of the lens that the fringe of the corpus ciliare 
is attached. Within the eye is the fluid vitreous humour. The eye is 
lined by a delicate layer of loose cells, underlaid by a pigment layer, and 
then the inner layer of the retina. 
Behind the eyeball, and forming as it were a cushion at its base, is a 
peculiar development of nervous tissue, the “ white body.” It consists of 
rounded or irregular, apparently nucleated cells. 
Auditory Organs. 
In the substance of the cephalic cartilage are excavated two auditory 
chambers, one on either side of the ridge already referred to. Their 
walls give rise to several rounded protuberances, which are most 
numerous on the side nearest to the nervous ring. The two cham- 
bers approach each other on the posterior side, where the dividing wall 
becomes thin and transparent. Each contains a single large otolith, 
composed of carbonate of lime. The otoliths, (pl. viii., figs. 12-14) are 
somewhat flattened, and are similar in shape, though one is a little larger 
than the other. The main portion of the otolith has one of its margins 
markedly convex, while the other is roughened and uneven, with two fairly 
well-marked excavations. From this mass the otolith narrows to an end. 
All the surface, except the roughened part referred to, is white and smooth 
so far as can be seen with a pocket magnifier ; but the microscope shows 
a rugose surface. 
EXPLANATION OF PLATES III.-VIII. 
PrarE 111,—Sepioteuthis bilineata. 
Pirate IV.—Dissection along posterior surface, showing position of organs. 
a, funnel. 
b,b, hinge cartilages. 
€,c, articular cartilages. 
d,d, musculi retractores infundibuli. 
e, penis. 
f, intestine. 
f’, ink-sac. 
9,9, branchie. 
h. descending aorta. 
v,v, veins from the mantle. 
k,k, branchial hearts with appendages. 
1, ascending aorta with arterial branches, 
