ORGAN OF TASTE IN EEPTILES. 327 



susceptible of impressions than in higher Reptilia ; the discoid 

 expansions of the toe-ends in Hyla, and the filamentary appen- 

 dages of the toes in Pipa, may have more sense of feeling than 

 other parts, but seem not to be applied in active touch. The 

 labial papillae of larval Frogs are so placed and supplied by nerves 

 as to suggest a tactile function. Certain Ophidians, e.g. Herpeton 

 tentaculatum, have a pair of tentacular appendages upon the 

 snout: but the long, extensile, forked, filiform tongue seems to 

 be used rather as an organ of exploration than of taste in most 

 Serpents, and in the slender-tongued Lizards. The expanded 

 toes of Geckos, fig. 162, the short, thick, scansorially-opposed 

 digits in Chameleons, and the concave surface of their prehensile 

 tail, although mainly modifications for locomotive purposes, may 

 well be supposed to have a surface more sensitive than other 

 parts of the body. The snout-like production of the upper lip 

 in TrionychidcR and Chelys, with the subsidiary tegumentary pro- 

 ductions of the head in the latter, are probably more direct and 

 active instruments of tactile exploration in these soft-skinned, 

 mud-haunting, and chiefly nocturnal Chelonia. Some nocturnal 

 Tree- Snakes (Dryophys, Passeritci) have a prolonged snout. 



62. Organ of Taste in Reptiles.- -The glosso-hyal, fig. 85, 42, 

 does not support, in Fishes, an organisation of soft parts for a 

 special sense of taste : and the description of the tongue and other 

 projections and structures in the interior of the mouth will be 

 given in connection with the preparatory digestive organs. A 

 tongue, as a gustatory organ, is as little developed in the perenni- 

 branchial Reptiles, and is absent in the marsupial Toads (Pipa). 

 There is as little trace of tongue during most of the larval period 

 in other Anura ; but, about the time when the fore limbs are in 

 bud, the membrane covering the basihyal begins to develope vas- 

 cular fungiform papillae, with looped capillaries and muscular fibre : 

 the whole mass growing and extending from before backward, and 

 constituting the retroflexed tongue, by the time the tail is atrophied. 

 The free part is usually bifid or bilobed. It is mainly an organ 

 of prehension, and will be described as such, together with the 

 tongue of the Chameleon, in connection with the organs of nutri- 

 tion. In the thick-tongued Lizards, e. g. Iguana tuber citlata, the 

 dorsum and sides of the tongue are minutely papillose ; in Tiliqua 

 scincoides they are coarsely papillose : both the food and the teeth of 

 these Sauria indicate a certain amount of mastication, with which 

 the sense of taste is correlated. In most Reptilia the food is bolted 

 entire. In the Tortoise ( Testudo indica) the tongue is beset with 

 numerous elongated and pointed papillae: in the Turtle (Chelone 



