280 THE CEPHALOPODA. §.243, 244, 245. 



CHAPTEli 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 organs, 

 which are situated on the head; and this animal has, beside the thirty-eight 

 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, consequently, froro 

 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 ojsophageal 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 olfactory papillae, to which they are distributed in a 

 ray-like manner.*^* 



1 Touch appears the oiily sense develoyjed with tilus this part of the tongue as having all thechar- 

 Hectocotylus. If Costa^s tigure (Ann. d. Sc. Nat. acteristics of a gustatory organ. With Sepia, the 

 XVI. PI. XIII, f\g. 2», e. f.) is exact, Hectocoty- soft papillae have already ))een figured by Savigny 

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

 organ on the anterior extremity of the body. in Firussac, loc. cit. Sepia, PI. IV. fig. 2'-, 3^1). 



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

 or Isis, 1835, Taf. III. IV., or Ann. d. Sc. Nat. time regarded as the external auditory passages, 

 XXVIII. PL II. fig. 1, PI. III. fig. 4. and the cutaneous folds sun-ounding them as a Pa- 



3 Owen and Valenciennes, loc. cit. PI. VIII. vilion {Firussac, loc. cit.), until Kblliker (Fro- 

 fig. 2, i. and PI. IX. fig. 1, i. riep's neue Notiz. XXVI. 1843, p. 166, and, E:it- 



1 This organization appears to have eluded the wickel. d. Cephalopoden, \k 107) discovered a 



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



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



with tlie Octopodii. Owen (On the Nautilus, p. 23, being poor m vibratile organs, it is quite desu-able 



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



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



.554, fig. 236,) and Valenciennes (loc. cit. p. 280, lium is likewise feebly developed. 

 PI, X. fig. 3, 4,), only, liave represented with Nau- 



