20 PHOLAS. 



animal is supposed to effect this operation by 

 means of a corroding fluid that is secreted in the 

 body, and which it has the power of ejecting upon 

 the substance into which it has entered. 



^' The Fholas has the power of emitting a 

 phosphoric liquor, which shines with brilliancy in 

 the dark. 



^' I must remind you that the accessory valves 

 are fixed to the margin of the shell by a gelatinous 

 substance ; this decays after the death of the 

 animal, and consequently the smaller valves are 

 frequently wanting. 



" The number of species is twelve. Several of 

 them are found on our coasts. The Pholas 

 genus is without colour, but the reticulations in 

 some species are exceedingly delicate. Pholas 

 Candidas (Plate 3) is found on the shores of 

 Kent ; you will be pleased with the shells. 

 Pholas dactylns is larger and coarser, and not 

 at all uncommon. 



" We have now finished our first division, and 

 must proceed to the bivalves." 



