308 Prof. Owen on the Structure of the Pearly Nautilus. 



distinct fasciculi from the dense cellular tissue (fig. 2. h), sur- 

 rounding the nerve in the centre of the tentacle (fig. 2. d), and 

 radiate at equal distances to the circumference ; they dinde and 

 subdivide as they diverge, and also send off lateral fibres, which 

 form a delicate network in the interspaces of the rays, especially 

 at the angles : the meshes include the longitudinal fasciculi, the 

 cut ends of which are shown at c, fig. 2. 



" The mechanical arrangement of the contractile fibres is very 

 similar to that of the complex muscles described by Cuvier in the 

 proboscis of the elephant. The attenuation and elongation of 

 this brobdignagian tentacle must be effected without compress- 

 ing the central breathing-tubes, and the transverse fibres accord- 

 ingly radiate from the dense ligamentous tissue which surrounds 

 the tubes : the same prospective contrivance is manifested to pre- 



vent the compression of the nerves 

 and vessels in the muscular system 

 of the ninety proboscides of the Nau- 

 tilus. 



" The papillEe upon the exterior 

 surface of the two large confluent di- 

 gital processes forming the hood, and 

 of the two hollow digitations next in 

 size immediately beneath them, form 

 a remarkable character in the Nau- 

 tilus, on account of their obdous 

 similarity to tactile papilke ; but the 

 sense of touch must be specially ex- 

 ercised by the numerous cephalic 

 Fig. 2. 



Fig.l, 



e\ r ..., -.. .r '-^ _^— __:=__^^ y Inner surface of a tentacle of 



Section of tentacle (Niutilu',) magnified Nautilus pompilius, magnified. 



tentacles, which, from their softness of texture, and especially 

 their laminated inner surface (fig. 2. e,f), are to be regarded as 

 organs of exploration not less than as instruments of prehension. 

 " I shall now submit my grounds for believing that the corre- 

 sponding organs in the Dibranchiate Cephalopods are the appen- 

 dages developed from the head, termed ' arms,' ' feet,' ' tentacles,' 



