ORGANS OF THE SENSES. 299 



consistence, and other physical properties of external bodies. 

 The almost naked skin of apodal anguilliform fishes, and the 

 great flexibility of their trunk, compensate, as in the per- 

 eimibranchiate amphibia and in the cetacea, for the imper- 

 fect development of their members as tactile organs, and 

 many fishes possess tentacular filaments of great sensibility, 

 and often very numerous near the mouth, as the sturgeons, 

 the silurus, the cod, and the lophius where they extend also 

 from along the sides of the body. The clawless feet, the 

 naked and delicate skin, and the broad fleshy tongue and 

 lips of the caducibranchiate amphibia greatly extend their 

 means of receiving impressions of touch ; and the long 

 forked tongue of serpents, during their intercourse with each 

 other, and during their progressive movements, is constantly 

 darted out and retracted, and employed as an organ of touch, 

 like the antennae and palpi of insects under similar circum- 

 stances. The soft webbed feet and partly clawless toes of 

 the crocodilian reptiles, and their broad fleshy tongue and 

 lips, compensate for the diminished sensibility produced by 

 the large ossious plates and horny scales covering the greater 

 part of their body, and enable them better to feel their prey 

 under the dark and muddy waters they inhabit. The broad 

 digital expansions of geckos and phylluri, the soft fleshy 

 feet and thin cutaneous coverings of the chamseleons, the 

 iguanas, the lizards, and other climbing sauria, and the broad 

 intercostal membranes of the dragons, contribute also to ex- 

 tend their sense of touch. As in all other aquatic animals, it 

 is chiefly among the aquatic forms of birds and mammalia that 

 we observe the naked and soft condition of the skin most 

 conducive to its sensibility, and the most extensive develop- 

 ment of this delicate organ of touch especially between the 

 digital phalanges, and the tentacular developments of the 

 invertebrata so often seen in the fishes, are still observed in 

 various fleshy prolongations from the face of birds, and even 

 of some quadrupeds as the condylura. It is, however, chiefly 

 in the long divided hands of carnivora, quadrumana, and all 

 the hightr forms of quadrupeds that we find the organs of 

 touch acquire their most appropriate and exquisite structure. 

 And in proportion to the high nervous development and 

 that of the sensitive cutaneous papillee, to the sensibility, 

 the vascularity, the flexibility and the softness of the fingers, 



