3 1 8 Introdiictio7i to A nimal Morphology. 



head-cartilage to the side of the mantle. The fin along the 

 side is moved by muscles attached to its cartilaginous support. 



The mouth is surrounded by an annular lip, at- 

 tached to the base of the arms by a buccal membrane. 

 Within this is a parrot-like beak of two dark brown, 

 vertical, conchiolin jaws, of which the under overlaps 

 the upper. Internal to these is a soft ciliated (taste r) 

 organ, in front of the vertical internal tongue, on 

 which is stretched the broad radula, armed with long 

 hollow lateral hooks, with a dental formula in each 

 row of 3-1-3, or (Eledone and Octopus) 4-1-4, or 

 (Nautilus) 4-5-4. Into the mouth open one or two 

 (Onychoteuthis, Eledone, Octopus) pair of large, 

 smooth, or lobed salivary glands. The posterior pair 

 is absent in Sepia, Loligo, &c. ; short and small in 

 Octopus and Eledone. In Nautilus there is a lateral 

 (salivary r) glandular mass on each side of the mantle. 



The oesophagus is narrow and long, dilating into 

 a fusiform crop in Nautilus. Argonauta has a long 

 oval crop, but in Octopodidas it is much shorter. In 

 Nautilus the oesophagus passes through a transverse 

 intermetameric septum, stretching between the head 

 segment (prosoma) and the visceral bag (metasoma). 

 The stomach is saccular, thick-walled (Octopus and 

 Nautilus*), ciliated within; the cardiac and pyloric 

 openings are close together, and the lowest part of 

 the stomach is saccular. The intestine begins with 

 a dilatation which in Nautilus is lamellar, in Loligo 

 is spiral, in Rossia is curved and round ; into this 

 open the two bile ducts. The longitudinally folded 

 intestine is moderately straight, and ends in the 



* In this animal having tendinous plates and thick cuticle, like a bird's 

 gizzard. 



