CONCHOLOGIA CESTRICA. I/ 



The Eye, is very small, and placed on, or near, the base 

 of the tentacles, and consists of the usual coats pertaining 

 to that organ, together with a lens. 



The Organ of Hearing, is composed of two auditive 

 capsules, placed on the posterior surface of the large 

 oesophageal ganglion (the brain). These capsules con- 

 tain several otolites, or small spherical bodies, composed 

 of carbonate of lime, immersed in a fluid, and possessing 

 a rotary or vibratory motion, derived from the vibratile 

 cilia within the capsules. 



The situation of the Olfactory Organ, has not been 

 satisfactorily ascertained. In the terrestrial species, it 

 is supposed to reside in a cnl de sac, between the lower 

 lip and the front of the foot. 



The Organ of Taste, is alike unknown ; but that 

 needful sense probably resides within the buccal cavity 

 which contains the lingual ribbon. 



The Oral Organs, are highly complicated the lip' 

 or palate is armed with a transverse arcuated maxillary 

 plate or jaw, either entire, or consisting of several pieces; 

 within this is an elongated strap of ligamentous or cor- 

 neous matter, called the Tongue, or Lingual Ribbon ; 

 the surface of which is thickly set with Sharp Siliceous 

 Teeth, beautifully arranged in rows, both transverse 

 and longitudinal, with the points turned inward. The 

 number of denticles varies from a few hundreds, to 

 many thousands. The tongue is very retractile, by its 

 own proper muscles ; and is an ingestive, as well as a 

 manducatory organ. When in use, it is quickly pro- 

 jected from the mouth in the form of a loop, and as 

 rapidly withdrawn. - 



The Alimentary Canal, is long, ai:d convoluted, and 

 some species are provided with Salivary Glands. 



The Kidneys, are sometimes present. 



The Liver, always. 



2* B 



