30 DIOESTIVE ORGANS. 



and resembling tliat of a parrot, Avitliin which is a flesh^^ tongue 

 armed witli teeth. These parts are envelojied in a large muscular 

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

 are two lips, themselves surrounded and in-otected b}' an ex- 

 tensible buccal membrane, situated between the buccal bulb and 

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

 to tlio 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 tlic exterior i)art of the moulh. It is encircled l\y 

 eight or ten Heshy aj^pendages, externally mnrked by as many 

 muscular ridges which correspond to the bands connected with 

 the arms. The 1)uccal membrane, doubtless assists in retaining 

 the food of the animal in juxtaposition with the mandibles, and 

 for this inirpose the fleshy appendages are provided at tlieir 

 internal extremity in th.e Calamaries and in Sepioteuthis with 

 cu])ules siniihii" 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 l)eak is corneous; with a more or less calcareous invest- 

 ment ill the tetrabranchiates. It ditfers from the beak of birds 

 in tli:it: the sii])erior mandible instead of covering the inferior, 

 shuts witliin it. Tlic superior mandible is composed of two 

 distinct parts, the one rostral, more or less arcuated, sharp in 

 front, forming behind a hood sejiarated 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 dirterence, that the lateral part is elongated on each 

 side and forms a wing, vaiying in form. 



Calcareous in Nautilus, Rhynchoteutliis and I'aleoteuthis, the 

 l)eak is infinitely larger, without hood in I'aleoteuthis, whilst 

 along with tiie hood there are wide calcareous wings in Kh^^nco- 

 teuthis. In the corneous-beaked species the superior mandible 

 has a vei-y short rostral portion but little sei)arated from the 

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

 Argonauts and Philonexis (Tremoctopus) ; very long, but little 



