﻿10 BRITISH FOSSIL CEPHALOPODA. 



flexure, as the pedal ganglia lie between the two directions of its parts. As, however, 

 the heart lies on the same side of the body as the pedal ganglia, as it does in many 

 other molluscs, the terms neural and hsemal would appear to be misnomers. Here the 

 intestine turns towards the heart and the other main portions of the circulating system. 



At the commencement of the intestine is the opening of a globular receptacle 

 (fig. 5, i) which is filled with broad parallel laminae, transversely ridged, and which 

 may itself be glandular. One of the laminae, longer than the others, prevents the 

 regurgitation of the secretion into the gizzard. On the opposite side to that on 

 which it opens into the intestine this receptacle communicates with the main duct 

 of the liver. This is a large organ lying at the sides of the crop. It is roughly 

 divisible into four lobes, with perhaps a fifth between them ; but it consists of 

 numerous, scarcely united, lobules of angular form, covered by delicate layers 

 of peritoneum. Each lobule consists of acini suspended either to the blood-vessels 

 or ducts, the latter of which gradually unite before entering the receptacle at the 

 entrance to the intestine. This receptacle Prof. Owen thinks may also serve the 

 functions of a pancreas. From it the intestine continues its course forwards, then 

 makes a backward fold, the two sides of which are united by a mesentery, and then 

 it passes forwards to the anus, which lies ventrally in the median line of the mantle 

 cavity, and opposite the bases of the lower branchiae, where it has swollen lips 

 (fig. 6,6). 



The cartilage which surrounds the oesophagus, supports the nervous ganglia, and 

 gives origin to several muscles, has a very peculiar form (fig. 7). Its under-surface 

 is tolerably flat in its general aspect ; it is widest in its rounded central part or 

 body, from whence a process or horn projects on each side, running forwards and 

 downwards into the base of the funnel. From the opposite side are also two pro- 

 cesses, which, however, instead of being straight like the others, curve out so as to 

 leave a circular opening between them, which forms a passage for the oesophagus. 

 The inner and under side of these, together with the body, are excavated in an 

 irregular circular groove, to support the ganglia on whose shape they are moulded. 

 On the upper side the body is produced into a prominence, whose flat, heart-shaped 

 surface faces upwards and backwards, the apex being away from the body of the 

 cartilage ; the horns have processes imbedded in the sides of the funnel. 



The principal muscles are — first, the shell-muscles. These are strong masses 

 which are attached at one end to the two halves of the heart-shaped cartilage-face 

 just described, pass obliquely backwards and outwards, to be attached to the large 

 patches where the mantle has made a horny deposit on the sides of the shell. There 

 seems to be some little doubt as to the amount of attachment that exists between the 

 muscle, the horny band, and the shell ; but Macdonald, the only writer who has seen 

 the animal in its fresh state, observes that the fasciculi of the muscles do not penetrate 

 the mantle nor become attached to the shell, and shows admirably how the contrao 



