BRACHIOPODA. 187 



23* Sinus and fold undefined and shallow. 



376. Reticularia /avis. 

 23* Sinus and fold defined and angular. 



CV. Martinia. 



22f Surface radially striate 326. Spiriferradiatus. 



22f Surface minutely granular (seen under lens). 



388. Amboccelia planoconvex a. 

 xx. Mesial fold and sinus reversed in position. 



CVIII. Metaplasia. 



xx. Mesial fold and sinus lacking or faint 23+. 



23f Beak of pedicle valve high and incurved ; that of 

 brachial not incurved. Shell nearly plano-convex. 



XXVI. Kutorgina. 

 23f Both beaks incurved. Shell bi -convex. 



3 80. Reticularia perplex a . 



2222. Surface plicated yy. 



yy. Shell structure punctate 24-f. 



24f Small 24*. 



24* Cardinal area present 20 // . 



20 // Cardinal area very high, giving the shell a 



semipyramidal form C. Cyrtina. 



20 // Width much exceeding length, the shell thus 

 lacking a semipyramidal aspect. 



CII. Spiriferina. 

 24* Cardinal area absent. Umbo of pedicle valve 

 truncated by a round foramen. 



CXII. Tre?natospira. 

 24f Large, spiriferoid, with pedicle tube or syrinx in rostral 



cavity of pedicle valve CVI. Syringothyris. 



yy. Shell structure not punctate 25-f. 



25f Low fold on pedicle valve and sinus on brachial. 25*. 

 25*, Shell pustulose, brachidium a spire. 



CXIX. Vitulina. 

 25* Shell not pustulose, brachidium absent. 



LX. Scenidium. 

 25 f Well marked sinus on pedicle valve and fold on brachial . 



26*. 



26* Cardinal areas of the two valves subequal in 



height ; plications angular, including fold and 



sinus; no brachidium LIII. Platystrophia. 



26* Cardinal area of pedicle valve greatly exceeding 

 that of the brachial ; brachidium spiral... 2i /r . 

 2i /r Cardinal area very high, form of shell sub- 

 pyramidal, deltidium perforated. 



CI. Cyrtia. 

 2i ,/ Cardinal area variable, form not subpyra- 

 midal, deltidium absent or without perfora- 

 tions... c< CIII. Spirifer 



