PfiOloz hy'] 



SNAILS' TEETH. 



The top left-hand photograph shows the elaborate set of the River Snail; the right-hand shows some of the Black Slug's 

 30,000 teeth. The teeth of the Common Snail occupy the bottom left-hand corner, and on the right , are" the fan-liUe teeth of 

 a-^apecjes of Fresh-water Snail, 



