1 Costal plates smooth. 



2 Costal plates tuberculated. 

 oo Alimentary canal petal shaped. 



Articulating surface of columnar joints radiated, 

 t Auxiliary side arms round. 

 I Auxiliary side arms placed irregular. 

 1 Costal plates with angular rugged 



striae. 

 ** Column pentangular. 



ooo Alimentary canal pentangular. 



Articulating surface of columnar joints radiated. 

 f Auxiliary side arms round. 



J Auxiliary side arms placed irregular. 

 1 Costal plates smooth. 



B Pelvis formed of three plates. 



1 Sp.planus. 



2 Sp. tuberculatus. 



3 Si 



4 Sp. quinqu angularit. 



% }j* 4 j {{H f 



Five costal and one -Hrtercostal plate resting on the pelvis. VII. GEN. ACTINOCRINITBS. 

 b Column not enlarging near the summit. 

 b Fingers formed of two series of joints. 

 * Column round. 



o Alimentary canal round. 



Articulating surface of columnar joints ra- 

 diated. 



t Auxiliary side arms round. 

 J Auxiliary side arms irregular. 



1 Thirty fingers proceeding from five 



scapulas. 



2 More than thirty fingers proceeding 



from five scapula. 



1 Sp. triacontadactyfas. 



2 Sp, polydactylus. 



Five intercostal plates, resting on the pelvis, in whose 



lateral angles five costal ones insert. VIII. GEM. RHODOCBINITBS 



b Column not enlarging near the summit, 

 b Fingers formed of two series of joints. 

 * Column round. 



oo Alimentary canal petal shaped. 



Articulating surface of columnar joints radiated, 

 t Auxiliary side arms round. 



I Auxiliary side arms irregular. * Sp. verus. 



Costal, or intercostal plates wanting the five scapulae, 



adhe'ing to the pelvis. 

 b Column not enlarging near the summit, 

 b Fingers formed of two series of joints. 



V. GEN. PLATYCRINITES. 



