84 PHOLAS. 



cimens represented in the wood in fig. 8. are young 

 shells of the same species, with the aperture exposed. 



There is no specific difference between the Ph. striata 

 and Ph. pusilla. Gualtieri has figured the shell, but 

 he has made it too broad. It was this circumstance 

 which probably led Linnseus to make the pusilla a dis- 

 tinct species, but he was evidently in doubt about the 

 matter. Some shells are shorter and broader at bottom 

 than others. Such are those figured under the name 

 of Ph. striata by Chemnitz, vol. 8. pi. 102. f. 864—866. 



It is not an English species, but brought to us in 

 ships from America and India. 



HOOKED PIERCER. 

 PI. 16. /. 5, 6, 7. Dr. Coombe. 



8. Pholas falcata. Ph. testa subovata, multifariam striata, apertura pa- 



tentissima, cardinis dentefalcato. 

 Shell somewhat oval, variously striated; aperture very large; hinge with a 



hooked tooth. 



This is a new species, distinguished by the singular 

 conformation of its tooth, which, after curving from 

 under the hinge in the usual manner, returns again so 

 as to give it the figure of a pruning-hook. The aper- 

 ture of the shell is very large, at the base of which, 

 where the valves unite, there is a little projection, or 

 nail, which proceeds from the interior of the shell, and 

 gives stability to the union. This appendage is com- 

 mon to the wood-piercers, and corresponds with the 

 external division of the striae. The shell is much 

 shorter and wider in proportion than the Ph. striata, 

 but is marked externally in the same manner. 



