i68 



Shell Life 



broad hinge-plate folds over and is attached to the 

 beaks, but there is no knob as in the last species. 

 The doivsal shield is exceedingly small, and of tri- 

 angular form. The animal is of a red-brown colour, 

 with long siphons ; these have the orifices fringed 

 with hranched filaments. It is a little more than 

 2 inches — sometimes as much as 4 — in length, and 

 has been found on many parts of our coasts embedded 

 in mica-schist, shale, oolite, Oxford clay, etc. 



The Paper Piddock (Fholadidea 2^ci2)yracea) has a 

 shell that is exceedingly thin and delicate, oval and 

 convex, the forepart with transverse 

 ridges cut into little teeth. The beaks 

 approach towards the centre of the 

 upper margin as in the last two species. 

 The broad hinge-plate is reflected over 

 the front. In addition to the short 

 apophyses, there is what may be re- 

 o^arded as a triano^ular cardinal tooth in 

 each valve. The dorsal shield consists 

 of two small plates, often united. At 

 the hinder end of the sliell there is a 

 remarkable horny cup surrounding the 

 siphons — which are entirely connected 

 throughout their length. This cup, 

 which is not found in young specimens, 

 appears to be the beginning of a sheath 

 to surround the siphons, but which is not further 

 developed in this species. It burrows in sandstone, 

 hard clay, peat, and submerged wood, chiefly along 

 the coasts of Devon and Cornwall, and at various 

 places round Ireland ; at low water of spring tides. 

 The Wood Piddock {Xylopltaga dorsalis) is a con- 



Paper Piddock 



