92 DIGESTIVE ORGANS. 



externally marked by as many muscular ridges which correspond 

 to the bands connected with the arms. The buccal membrane 

 doubtless assists in retaining the food of the animal in juxtapo- 

 sition with the mandibles, and for this purpose the fleshy 

 appendages are provided at their external extremity in the Gala- 

 maries and in Sepioteuthis with suckers similar to those found 

 on the arras. 



The lips, of which the external one is thin, always short and 

 with entire border, and the internal, in contact with the beak, 

 thickened, fleshy and papillary or ciliated upon its edge, can be 

 contracted over the beak, so as to cover it entirely, fulfllling 

 functions analogous to the lips in mammalia. 



The beak is corneous (ix, 95 ; xxiii, 2, 3 , with a more or less 

 calcareous investment in the tetrabranchiates. It differs from 

 the beak of birds in that the superior mandible instead of 

 covering the inferior, shuts within it. The superior mandible is 

 composed of two distinct parts, the one rostral, more or less 

 arcuated, sharp in front, forming behind a hood separated by an 

 inferior expansion varying in length or breadth according to the 

 genus. The inferior mandible, always larger, has a less sharp 

 rostrum, and is also composed of a rostral portion and an 

 inferior expansion ; but with this difference, that the lateral part 

 is elongated on each side and fonns a wing, varying in form. 



The fleshy tongue (ix, 98), is armed above with many trans- 

 verse rows of recurved, spinous teeth, the arrangement of which 

 differs in the various genera. Ordinarily, as in the dibranchiates, 

 we find the series of teeth to consist each of a central one with 

 three side-teeth on either side of it, and sometimes, as in 

 Eledone and Loligo, an additional plate on either side ; but in 

 iS^autilus we find a modification in five somewhat quadrangular 

 central teeth of which the middle one has the most pointed end, 

 and on either side two long fangs with a much smaller plate at 

 the base of each — in all thirteen teeth in a series. The central 

 teeth, which are simple in Sepia and Sepiola, are tricuspid in 

 Loligo and denticulated in Eledone ; whilst the lateral uncini 

 are usually claw-like. Fifty rows of teeth may be found on the 

 tongue of the Sepia ; their continuous growth compensates the 

 loss by abrasion. 



Under the tongue is found a flesh}^ mass covered with papillae, 

 which is supposed to be the organ of taste ; and in Nautilus we 

 find similar papillae on the tongue (behind the teeth), to its 

 entrance into the gullet. 



The rounded, sack-like stomach which is situated towards the 

 middle or end of the body is connected with the mouth by a long- 

 central gullet ; and the intestine, more or less bent upon itself 

 ends in a medial, ventral anus. 



One or two pairs of salivary glands are present in the dibran- 



