PLATE XXXIX. 



Helix fluvlatllis depressa major, anfractibus quatuor, ex utraque parte 

 circa uinbilicum cava. Cornuarietis. Tab. 4. fig. 

 13. Da Costa Br. Condi, p. 60. tab. 4.-. fig: 13. 



Purpura. S. Cochlea fluviatilis comprcssa major. List. Exerc^ 

 Anat. 2. p. 50. 



T he adult shells of this species are from three quarters of an inch, 

 to an inch and a quarter in diameter ; the colours various, generally 

 brownish or ashen colour, inclining in some to red, in others to yellow ; 

 the young shells are whitish and more transparent. 



It is very common in ponds and rivers. The animal is blackish 

 brown, and has two red capillary horns *. 



The Helix Nana, or Dwarf of Pennant, fig. 125, is considered by 

 Da Costa and other conchologists, as a young shell of this species. 



* " This fish emits a fine searkt humour, if a grain of salt of any kind, or a little 

 pepper or ginger, be put into the mouth of the shell. It emits this fine scarlet humour 

 all the year, especially in April and September. Dr. Lister gives a full account of ir. 

 He says, this scarlet humour may be readily got, and in great quantity, if a large 

 parcel of these shells be wrapped up in a cloth bag, sprinkling over it a little salt; tho;i 

 the scarlet liquor will ouze plentifully. The colouring part of tliis humour immediately 

 subsides, if sprinkled with powdered allum, and the rest of it remains like clear water. 

 The colouring part may be strained through a filtering paper, but the elegance of its 

 colour is lost, and it changes into a dull, unp'cas.'.nt rusty brown. Moreover, if mixed 

 with vinegar, spirit of wine, deliquated vegetable salts, or common snlt dissolved, this 

 elegant scarlet colour perishes in the same manner as when mixed with allum. Neither 

 can this liquor be kept by itself pure ar.d unmixed; for in vain did the doctor strive to 

 preserve it in narrov/ mouthed bottles or phials, perfectly well closed, and with oil or 

 honey thrown over it. Thus this colour is of so fugitive a nature, that no acid or 

 astringent has been found sufficient, to preserve tlie elegance of its tint." 



•' Dr. Lister further recites some observ.-.tions and experiments he made on tlii* 

 scarlet fluid, to discover whetlier it was a humour of the body, or to be got by lace- 

 ration or incision, as blood ; a saliva from the throat or stomach ; or a particular hu- 

 mour contained in certain vessels or parts ; but the nicety and difficulty of the experi- 

 BJeiUs rendered it impossible for him to deteimiae it precisely.'" Da Costa, page 6ij 62> 



