BRACHIOPODA. 181 



6* Hinge line straight with flattened margins 7 // . 



7 //r Pedicle valve prolonged posteriorly and 

 acutely triangular, flattening from large 



deltarium LXXV. Rhynchotreta. 



7 // Pedicle valve not prolonged posteriorly ; flat- 

 tening a cardinal area in each valve. 



LXXIII. Orthorhynchula. 



6* Hinge line curved, no flattening 8 // . 



8" Pedicle valve with deeply excavated muscu- 

 lar scars, sinus forming nasute anterior pro- 

 longation LXXXIII. Eatonia. 



S // Pedicle valve with muscular scars not deeply 



excavated c /f . 



c" Shell structure punctate. 



LXXXIV. Rhynchopora. 



c" Shell structure not punctate 3 /// . 



3 /// Pedicle valve with pseudo area and 

 strong teeth supported by lamel- 

 lae ; brachial valve with septum 

 entire. 



LXXXV. Rhynchonella. 

 y // Small teeth with slender lamellae, 

 septum of brachial valve exca- 

 vated posteriorly a /// . 



a /// Plications low and rounded. 

 LXXVIII. Leiorhynchus. 

 a f,f Plications sharp and angular. 

 LXXVI. Camarotcechia. 

 Shell terebratuloid or athyroid — Typically no flat cardinal area. Hinge 

 line curved. Beak incurved, often truncated by foramen. Median 

 sinus and fold often absent ; when present usually broad and ill-de- 

 fined. Radiating plications or striae usually absent ; when present they 

 are never angular; arms generally supported by calcareous brachidium. j. 



j. Shell smooth, calcareous brachidium present 333. 



333. Median sinus and usually fold present mm. 



mm. Beak of pedicle valve truncated by a round foramen.. 8f. 

 8f Length and breadth subequal, brachidium a spiralium. 



7*. 

 7* Shell usually small (about ^ inch long or less). 



CXXIII. Seminula. 

 7* Shell of medium size, margins of sinus rounded. 



CXXIV. Meristella. 



J* Shell of medium size, margin of pronounced and 



broad sinus angulated, fold with median groove. 



CXXV. Pentagonia. 



8f Length greater than breadth, brachidium a simple loop. 



8*. 

 8* Beak of pedicle valve prolonged and greatly in- 

 curved over opposite valve. Pedicle opening 

 large XC. Vie/asma. 



