30 DIGESTIVE ORGANS. 



ami resembling that of a parrot, within which is a fleshy tongue 

 :mned with teeth. These parts are enveloped in a large muscular 

 bulb which supplies the force to the jaws. External to the beak 

 are two lips, themselves surrounded and protected by an ex- 

 tensible buccal membrane, situated between the buccal bulb and 

 the bases of the arms. Whilst the buccal membrane is wanting 

 to the octopods, it is well marked on the contrary in the deca- 

 pods. In development it forms a vast funnel, and in repose it 

 covers all the exterior part of the mouth. It is encircled by 

 eight or ten fleshy appendages, 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 juxtaposition with the mandibles, and 

 for this purpose the fleshy appendages are provided at their 

 internal extremity in the Calamaries and in Sepioteuthis with 

 ou pules similar to those found on the arms. 



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, fulfilling 

 functions analogous to the lips in mammalia. 



The beak is corneous; with a more or less calcareous invest- 

 ment 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 bread! li according to the genus. The 

 inferior mandible, always larger, lias 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 forms a wing, varying in form. 



Calcareous in Nautilus. Hhynchoteuthis and Paleoteuthis, the 

 beak is infinitely larger, without hood in Paleoteiithis, whilst 

 along with the hood there are wide calcareous wings in llhyneo- 

 teuthis. In the corneous-beaked species the superior mandible 

 has a very short rostral portion but little separated from the 

 expansion in Octopus; stilJ but little separated but wider in the 

 Argonauts and I'hilonexis (Tremoctopns) ; very long, but little 



