CONCHIFERA OR BIVALVES. 125 



80. Plicatula. Shell irregularly ovate, 

 inequivalve, one valve being more 

 convex than the other, sides strongly 

 and transversely grooved ; ligament 

 internal, between the teeth ; bosses 

 unequal. Animal unknown. — 5 



species recent, and 10 fossil. 



Attached by the under valve to stones, &c. 



81. Spondylus. — Shell eared, inequivalve, 

 rough, with spines and plaits; 

 two strong teeth, uniting the 

 valves closely; bosses unequal, 

 that of the lower valve pro- 

 jecting ; ligament internal. 

 Animal, foot very indistinct. 

 — 21 species recent, and 9 

 fossil. 



The Spondylus lives at great depths in the 

 sea, and attaches itself to corals, &c. : it has 

 often been found fixed to anchors, cannons, and 

 other iron articles that have been for some time 

 at the bottom of the sea. Many of the species 

 are very beautiful, and of very vivid colours, 

 such as bright red, pink and yellow, or orange. 

 A fine collection of these beautiful shells forms 



