CONCHIFERA OR BIVALVES. 51 



has two short cardinal processes, and 

 a rather irregular space, extending 

 from the hinge to the boss. The 

 upper valve is rather flat, and has 

 a small obtuse appendage near the 

 base, and two processes closely lock- 

 ing into those of the lower valve. 

 Animal not known. — 1 recent and 3 fossil 

 species. 



From the Mediterranean. The interior of 

 the upper valve is very curious, being indented 

 as if to fit certain parts of the body. These 

 marks spread round in a semicircular direction 

 from the hinge, and look exactly as if they 

 were picked out in wax. The inside of both 

 valves is of a very pale green colour, and finely 

 granulated. 



4. Crania. — Shell compressed, somewhat 

 square, inequivalve, equi- 

 lateral, the upper valve con- 

 vex and patella-shaped, the 

 lower flat and attached. The 

 interior of the latter exhibits four very dis- 

 tinct muscular impressions. There are no car- 

 E 2 



