CATALOGUE 



OF 



BRACIIIOrODA OR LAMP-SHELLS 



IN 



THE BRITISH MUSEUM. 



Class II. BRACHIOPODA. 



Shell inequivalve, equilateral, attached by a muscular peduncle, 

 or by the surface of one valve, or fi-ee ; valves applied to the 

 dorsal and ventral sides of the animal, ixnited by muscles and 

 mostly articulated by teeth ; dorsal valve* usually smallest, always 

 free, fui-nished internally with sockets for the hinge-teeth, and 

 with shelly processes f for the support of the animal ; ventral 

 valve usually largest, and with its umbo produced and j)erfoiated 

 for the passage of the peduncle, frequently attached by its outer 

 surface, and generally provided internally with two prominent 

 teeth ; periostracum thick, sometimes developed into concentric 

 lamellsc. 



Animal furnished with elongated labial ap))endages, or oral 

 arms, which are free or united by membrane and variously folded, 



* What is here called the dorsal valve has often been called the Imver 

 valve, being usually below when the animal is in its natural position 

 attached to marine bodies ; but it has been found to cover the back of 

 the animal. 



t Sometimes termed an "internal skeleton" or "apophysary 

 system." 



B 



