-80 THE CEPHALOPODA. ^ 243, 244, 245. 



CHAPTER V. 



ORGANS OF SENSE. 



§ 243. 



The sense of Touch is well developed with the Cephalopoda, and is situ- 

 ated in the whole cutaneous envelope, in the fringed labial membranes, and, 

 especially, in the arms.*" Nautilus is particularly rich in tactile oro-ans, 

 which are situated on the head; and this animal has, beside the tliirty-eit'ht 

 tentacular arms, two external, and two median, large, labial prolongations, 

 placed about the mouth, the border of which has twelve small, curled 

 filaments, whose internal structure quite resembles that of the arms. 



The nerves of the filaments of the two external of these prolongations 

 have an origin common with those of the arms, arising, consequeirtly, from 

 the front border of the anterior cerebral band. Those of the filaments of 

 the median prolongations arise from the same band (but nearer the median 

 line), by two common roots which, before dividing, have a flat ganglion.*^* 

 This animal has, also, four other curled tentacles, which can be retracted in 

 a sheath, two in front of and two behind, the eyes. These tentacles receive 

 a special tactile nerve, which has its origin by the side of the optic nerve. ''^^ 



§244. 



With the Cephalopoda, the' fleshy point of the tongue is undoubtedly a 

 Gustatory organ. It is concealed in the anterior angle of the lower jaw, 

 and its rounding surface is covered with numerous soft villosities, which very 

 probably serve as gustatory papillae. *'' 



§ 245. 



The Olfactory organs of the Cephalopoda are situated in the neighbor- 

 hood of the eyes, and consist, each, of a cavity with tumid borders, or of 

 a cutaneous fossa which has an opening, and, sometimes, at the bottom, a 

 whitish papilla. The nerves of these organs arise from the optic ganglion 

 of the oesophageal ring, near the optic nerves. At first, they are closely 

 united with these last, enter the orbit with them, and extend along its poste- 

 rior wall, thence to the olfiictory papillae, to which they are distributed in a 

 ray-like manner.'" 



1 Touch appears the only sense developed with tiliis this part of the tongue as having all thechar- 



Hectocotjjlus. If Costa's figure (Ann. d. Sc. Nat. acteristics of a gustatory organ. With Sepia, the 



XVI. PI. XIII. fig. 2^ e. f.) is exact, Hectocoty- soft papillae have already litt-n figured by Savigny 



Ins argonautae has a special tentacle-like tactile (Descript. de I'Egypte, loc c-it. I'l. I. fig. 4, 5, and 



organ on the anterior extremity of the body. in Feni.ssac, loc. cit. Sepia, I'l. IV. fig. 2-, 3-). 



^ Owen, On the Nautilus, PI. IV. PI. VII. fig. 1, 1 The cavities here mentioned were for a long 



"r .^'''' ■^*^^i 'J^'^f- III- 1^-1 '"■ Ann. d. Sc. Nat. time ri-gardod as the external auditnry passages, 



X.XVIII. PI. II. fig. 1, PI. III. fijj. 4. and the cutaneous folds surrounding them as a P.i- 



•■) Owen and Fa/enciennes, loc. cit. PI. VIII. vilion (Ferussac, loc. cit.), until Kolliher (F> o- 



fig. 2, i. and PI. IX. fig. 1, i. riep's neuc Notiz. XXVI. 1S4;3, p. 1B6, and, K ,t- 



1 This organization appears to have eluded the wickcl. d. Cephalopuden, p. 107) discovered a 



observation of most naturalists. I have seen it special nerve, and declared, with reason, that the 



very distinctly, not only with tf ; Loligina, but also whole was an olfactory organ. The Cephalopoda 



with the Octoimda. Owen (On the Nautilus, p. 2o, being poor in vibratile organs, it is quite desirable 



PI. \T.II. fig. 7, or, Isis, p. 20, Taf. II. or, Ann. d. to ascertain if those olfactory organs are ciliated, 



Sc. Nat. p. 113, PI. IV. fig. 7, and Cyclop. I. p. for they are so in fishes witli which ciliated epithe- 



.5.'>4, fig. 2;J6,) and yalenciennes (loc. cit. p. 2S0, Uum is likewise feebly developed. 

 I'l. X. fig. y, 4,), only, have represented witli Nau- 



