:;o DIGESTIVE ORC.ANS. 



and resembling that of n. parrot, within which is a lloshy tongue 

 armed with teeth. These parts are enveloped in a lar^e muscular 

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

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

 tensible bueeal membrane, situated between the, bueeal bulb and 

 the bases of the arms. AVhilst the buccal membrane is wantin"' 

 lothenrlopnds.it is well marked on the contrary in the deca- 

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

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

 eiu'ht or ten lleshy appendages, externally marked by as many 

 muscular ridges which correspond to the bands connected with 

 the arms. The bueeal membrane, doubtless assists in retaining 

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

 for this purpose the lleshy appendages are provided at their 

 internal extremity in the Calamaries and in Sepioteuthis with 

 oupules 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, lleshy and papillary or ciliated upon it s ed^e. can he 

 contracted over the beak, so as to cover it entirely, i'ullillino; 

 functions analogous to the lips in mammalia. ^ 



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

 ment in the tetrabranchiates. It di tiers from the beak of birds 

 in that the superior mandible instead of coverino- 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 ovrnis. The 

 inferior mandible, always larger, has a less sharp rost rum. 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 win^. varying in form. 



Calcareous in Nautilus. Uhyndioteiit his and Paleoteiit his, 1 he 

 beak is infinitely lariier, without, hood in I'aleoteiit his. whilst 

 alon- with the hood there are wide calcareous wind's in IJhvnen- 



teuthis. [n the corneous-beaked species the superior mandible 



has a very short rostral pnrtinn but little separated IVnm the 

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

 Argonauts and Philmiexis ( Tremoclopiis) ; verv lon^. but lit 1 le 



