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ganglia, which give off ten large nerves, one to each arm ; they 

 also supply the siphon. The auditory nerves also arise from 

 the pedal ganglia, although their fibres may be traced to the 

 cerebral. The pedal ganglia are partially marked off from the 

 fused pleural and visceral by the presence of a small foramen 

 through which a blood-vessel passes. From the pleural por- 

 tion of this compound nerve centre a stout nerve passes to the 

 stellate ganglion, situated at the angle between the mantle and 

 the head. It can be seen shining through the integument 

 when the mantle cavity is exposed. From this ganglion nerves 

 radiate to the muscles of the mantle. The visceral half of the 

 fused ganglion gives off a pair of stout visceral nerves, which 

 unite to form a loop. These visceral nerves supply the gener- 

 ative organs, the kidneys, and other viscera, and each sends a 

 stout branch to a ctenidium. 



The eyes of Se'pia. are of great complexity. They have a 

 striking but superficial resemblance to the Vertebrate eye, and 

 fundamental differences exist between these two types of visual 

 organs. Anteriorly the eye is covered by a transparent cornea, 

 which in Se'pia, is closed. The cornea is protected by certain 

 folds of skin, which can cover it in by the contraction of a 

 sphincter muscle, and there is also a horizontal lower eyelid. 

 Within the cornea is the anterior chamber of the eye, into 

 which the folds of the iris project ; they partially cover the 

 lens, which consists of an outer and an inner part separated by 

 a membrane. The lens is supported by the ciliary body, which 

 with the lens occupies the anterior half of the retinal chamber. 

 The retina, which completes the wall of this chamber, is two- 

 layered, and the nerves which pass to it from the optic ganglion 

 enter the retina posteriorly. 



The auditory apparatus consists of two otocysts sunk in 

 the cephalic cartilage. Their cavities have an irregular shape, 

 and are lined by an epithelium, which is ciliated in places, 

 they contain an endolymph, in which a single spherical otolith 

 floats. 



An olfactory function is attributed to two small invagina- 

 tions of the skin, situated one just behind each eye. The sacs 

 open to the exterior by a small slit -like aperture; they are 

 lined by a ciliated columnar epithelium, amongst which are 



