﻿BRITISH FOSSIL CEPHALOPODA. 15 



The organ of smell is in close connection with the eye. It rises like another 

 tentacular sheath from behind the eve ; but its orifice, instead of being round, is 

 slightly expanded at the sides and covered by a tubercle arising from the proximal 

 side, so that its aperture is oblique and complex. This leads into a hollow cavity, 

 whose interior is thrown into folds like the barbules of a feather : it is supplied by 

 a large nerve direct from the upper commissure : its form and its homologous 

 position to similar organs in the Dibranehiates have left no doubt of its function, 

 though it was looked upon by Macdonald as representing an external ear. 



The organ of hearing is, in fact, seated immediately beneath it, as was discovered 

 by Macdonald. It is situated at the junction of the two commissures, whence its 

 nerve is derived, and consists of a little convex capsule resting in a depression 

 excavated in the cartilage. Its contents are minute bodies of calcareous nature — 

 " otoconia," of fusiform shape, floating freely in the cavity, or uniting together 

 in pairs. 



The reproductive organs of the female consist of the following parts. The ovary 

 lies in the hinder part of the body ; and in its undistended state, in which alone 

 it seems to have been hitherto found, is confined to the left side of the gizzard, 

 which it slightly overlaps below. It is contained in a fold of the peritoneum, and 

 opens with a puckered margin into the visceral cavity at its anterior end. It is thus 

 not continuous with the oviduct, but the apertures of the two face each other. 

 Within the ovary are found a number of pyriform capsules, opening inwards, and 

 attached at their blind ends to the inner surface of the sac — they are most crowded 

 together near the entrance of the nutrient vessels. The oviduct leads down by the 

 side of the intestine to a prominent and ridged aperture which lies on the right side 

 of the animal near the base of the funnel. Connected with the female generative 

 organs is a large gland, imbedded between the coats of the mantle on its ventral 

 side, some little way in front of the horny annulus. It thus lies in close apposition 

 to the convex part of the shell. Internally it consists of three parts; on each 

 side there is a large oval mass, which makes a prominent feature on the surface of 

 the mantle (fig. 1, h) when the animal is removed from its shell; and connecting 

 these is a transverse portion. They all consist of a number of parallel laminae 

 (fig. 6, /), which run transversely in the central portion and obliquely in the other 

 parts. These are made of perpendicularly set nucleated cells which secrete albumen. 

 The apertures from this gland are a number of minute openings in a groove formed 

 by a transverse fold of membrane, which rises into a pair of small prominences near 

 the middle line. The secretion is thus brought into proximity with the oviducal 

 aperture ; and as it affords, in all probability, a covering for the eggs, the gland 

 must be a nidamental gland. 



The male organs of generation, as described by Yan der Hoeven and Keferstein, 

 are as follows : — In the same position as the ovary in the female, lies a large testis. 



