TEREBRATULAD^. 



81 



branched dicliotomouslj. Animal with long arms 

 coiled in conical spires of many turns, directed 

 towards the dorsal valve, not supported by a shelly 

 framework ; mantle fringed with a few short 

 bristles. 



Hijpothyris (Phillips). Shell sharply beaked, 

 plaited; dorsal valve elevated in front, depressed 

 at the sides ; ventral flattened ; hinge-plates sup- 

 porting two slender curved pieces. 



H. psittacea. Fig. 121', n. s. 



122 



123 



Family III. Terebratulad^. 



Shell rounded or ovate, attached by a footstalk ; 

 ventral valve with a prominent beak, and two curved 

 hinge-teeth ; dorsal valve with a prominent pro- 

 cess between the hinge-sockets. Animal with 

 arms united to each other by a membrane, sup- 

 ported by a shelly loop. 



Terehratula (Brug. ). Lamp. Shell round; 

 perforation small, circular ; loop short, simple, 

 attached by its branches to the hinge-plate. Animal 



