280 



THE CEPHALOPODA. 



»5» 243, 244, 245. 



CHAPTEU 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, 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 surfice is covered with numerous soft villosities, which veiy 

 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 olfactory papillae, to which they are distributed in a 

 ray-like manner, ^'^ 



1 Touch appears the only sense developed with 

 Hectocotylus. If Costa's figure (Ann. d. Sc. Nat. 

 XVI. PI. XIII. fit;. 2», e. f.) is exact, Hectocoty- 

 lus argoiiautae has a special tentacle-like tactile 

 organ on the anterior extremity of the body. 



2 Owen, On the NautUus, PI. IV. PI. VII. fig. 1, 

 or Isis, 1835, Taf. III. IV., or Ann. d. Sc. Nat. 

 XXVIII. PI. II. fig. 1, PI. III. fig. 4. 



3 Owen and Valenciennes, loc. cit. PI. VIII. 

 fig. 2, i. and PI. IX. tig. 1, i. 



1 This organization appears to have eluded the 

 observation of most naturalists. I have seen it 

 very distinctly, not only with the Lohgina, but also 

 with the Octopoda. Owen (On the Nautilus, p. 23, 

 PI. nil. fig. 7, or, Isis, p. 20, Taf. II. or, Ann. d. 

 Sc. Nat. p. 113, PI. IV. fig. 7, and Cyclop. I. p. 

 654, fig. 230,) and Valenciennes (loc. cit. p. 280, 

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



tilus this part of the tongue as having all the char- 

 acteristics of a gustatory organ. With Sepia, the 

 soft papillae have already been figured by Savigny 

 (Descript. de I'Egypte, loc. cit. PI. I. fig. 4, 5, and 

 in Firussac, loc. cit. Sepia, PI. IV. fig. 2-, 3'*). 



1 The cavities here mentioned were for a long 

 time regarded as the external auditory passages, 

 and the cutaneous folds surrounding them as a Pa- 

 vilion (^F^russac, loc. cit.), until Kiilliker (Fro- 

 riep^s neue Notiz. XXVI. 1843, p. 166, and, Eut- 

 wickel. d. Cephalopoden, p. 10") discovered a 

 special nerve, and declared, with reason, that the 

 whole was an olfactory organ. The Cephalopoda 

 being poor in vibratUe organs, it is quite desirable 

 to ascertain if these olfactory organs are ciliated, 

 for they are so in fishes with which ciliated epithe- 

 lium is likewise feebly developed. 



