GHAP. II. 



SENSES OF REPTILES. 43 



which terminate the tentaculse of the animals, are in- 

 cipient developments of these organs (fig. 10.). It has 

 been generally supposed that, in this order of the Mol- 

 lusca, the eyes were merely rudimentary; but the recent 

 knowledge that has been gained of the animal inha- 

 bitants of the wing shells (Strombidee), shows that this 

 idea is erroneous. The eyes of the genus Pteroceros 

 have beautifully coloured irides; and those of the large 

 pink-mouthed Strombus, so often seen as chimney or- 

 naments, have been described to us, by a gentleman 

 recently returned from the West Indies, as large, bril- 

 liant, and as fully developed as those of the Cephalo- 

 poda, or cuttlefish. Among the testaceous univalve shells, 

 as well as in the slugs, the mouth and lips are fully 

 developed and as some of them live upon animals, 

 some on vegetables, and others as the large garden 

 slug on both, it follows that their sense of taste is 

 as perfect as in most other animals. The Cephalo- 

 poda, from connecting the Mollusca to the Verte- 

 brata, are still further organised, since it is among 

 these that the first rudiments appear of the organs of 

 hearing. 



^53.) Chelonian reptiles next succeed in the scale of 

 animal life; and the tortoise, being the first develop- 

 ment of the vertebrated structure, is eminently dis- 

 tinguished from those hitherto noticed, by possessing 

 the organs of smelling ; so that it thus exhibits the union 

 of all the five senses. It does not, however, appear to be 

 gifted with acute sensation ; but is, perhaps, more than 

 any other vertebrated animal, tenacious of the vital 

 principle ; a fact proved by the many cruel and dis- 

 graceful experiments of Redi, one of which consisted 

 in the extraction of the entire brain from the head ; after 

 which operation the animal walked about as before; 

 and though it afterwards closed its eyes, and never 

 again opened them, it yet survived for the space of six 

 months. Differences, indeed, although much slighter 

 in degree, will be found among every separate genus 

 with regard to their physical sensibility. Even animals 



