` 
15 
1 Costal plates smooth. . i Sp. planus. 
2 Cosial plates tuberculated. 2 Sp. tuberculatus, 
oo Alimentary canal petal shaped. 
§ Articulating surface of columnar joints radiated. 
+ Auxiliary side arms round. . 
L Auxiliary side arms placed irregular. _ 
1 Costal plates with angular rugged 
strie. 3 Sp. rugosus. _ 
** Column pentangular. £ 
ooo Alimentary canal pentangular- 
§ Articulating surface of columnar joints radiated. 
+ Auxiliary side arms round, | 
f Auxiliary side arms placed irregular. 
1 Costal plates smooth. 4 Sp. quingu angularis, 
B Pelvis formed of three plates. 
% Five costal and one intercostal plate resting on the pelvis. VII, GEN, AcTINOCRINITES.. 
b Column not enlarging near the summit. 1 
b Fingers formed of two series of Joints. 
* Column round. | 
o Alimentary canal round. 
$ Articulating surface of columnar joints ra- 
diated. 
+ Auxiliary side arms round. 
1 Auxiliary side arms irregular. 
1 Thirty fingers proceeding from five 
scapula. 
2 More than thirty fingers proceeding 
from five scapula. | 
1 Sp. triacontadactylus. 
2 Sp. polydactylus. 
& Five intercostal plates, resting on the pelvis, in whose | 
lateral angles five costal ones insert. VIII. Gen. RHODOCRINITES 
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. 
+ Auxiliary side arms round, 4 
+ Auxiliary side arms irregular. 1 Sp. verus. 
D Costal, or intercostal plates wanting the five scapulz, 
|. V. Gen, PLATYCRINITES. 
adhering to the pelvis. i 
b Column not enlarging near the summit. 
b Fingers formed of two series of joints, 








