38 



the intestine, being prevented from entering into the 

 spiral caecum by the folds of the wall in this region. 



(7) In the intestine digestion is finished, as some 

 proportion of the digestive fluid enters here. This region 

 is, however, chiefly that of absorption. After this, the 

 waste matter passes up to the anus and is ejected. 



The Ink Sac, or anal gland of Eledone is a long, 

 somewhat pear-shaped gland, which opens into the dorsal 

 wall of the rectum, on a slight papilla, very near the 

 anus (PI. IV, fig. 30, /. p.). It is a much less developed 

 structure than the ink sac of the Decapoda, and, unlike 

 the latter, lies embedded in a groove on the ventral surface 

 of the liver, in a median position (PI. VIII, fig. 32). To 

 expose it, the visceral envelope, and then the common 

 iridescent membrane round the liver and ink sac, must 

 be removed. Its dorsal wall lies in close contact with the 

 ventral epithelial wall of the liver. When the enveloping 

 membranes have been removed, the ink sac shows as a 

 dull metallic dark-blue organ. Great care must lie 

 taken not to cut the wall, for the thick viscous 

 secretion is exceedingly hard to get rid of, and stains the 

 dissection deeply. The nerves should be traced before 

 removing the visceral envelope. They come from two 

 sources in Sepia, and probably also in Eledone (Girod). 

 However, only those from one source have been followed 

 out, i.e. : — 



(1) The visceral nerves running over the liver, in the 

 neighbourhood of the ink sac, send several branches 

 inwards, which end in its walls (PI. VIII, fig. 31, 

 I S 1 N x ). Near the posterior end of the sac. a specially 

 large nerve runs in from each visceral trunk, and this, 

 after pursuing a downward course until it meets the 

 artery and vein of the ink sac, enters the gland along 

 with them (fig. 31, I.S.N.). 



