MOLLUSCOIDEA. 109 



Class II. Brachiopoda. 



All marine, with bivalve shell (valves unequal, but symmetrical) and 

 lophophore (horseshoe-shaped or in the form of two spiral arms). There 

 is an enteroccelic body-cavity, and two or four nephridia. Larva vermi- 

 form. Mostly fossil. 



Order 1. Ecardines, shell hingeless ; an anus. Lingnla antiqua. 

 L. anatina, recent. 



Order 2. Testicardines, shell with hinge and (usually) a calcareous 

 support for the arms ; no anus. Productus, fossil ; E-hynchonella, 

 with short two-limbed, Spirifera (fossil) with spiral, Terebratula with 

 loop-shaped arm-support. Argiope. 



