286 
The American Geologist. 
May, I8yl 
FOVK.E. 
SEPTA. 
Seemingly none. 
One, well defined. 
One, quite well marked. 
L'.".. None indicated 
26. 
27. 
28. 
29. 
30. 
31 
32 
33. 
Regularly radiate ; those of first order always reach 
center; secondaries much shorter. 
Regularly radiate, very strong, equal. 
false columella. 
Extend to 
Sharp edged, sub-equal or alternating, inner edges 
twisted together frequently. Generally rounded 
near wall. 
Extend nearly to center, small secondaries are gener 
ally present. 
One, well marked. Two 
smaller lateral ones. 
None indicated. 
Radiate, alternate. Primaries unite towards center 
and are irregularly twisted. 
One is present. 
34 
35. 
36. 
37. 
38. 
39. 
40. 
41. 
42. 
43 
44. 
45. 
46. 
47 
48 
None indicated. 
One, which is generally 
well marked. 
Thin, straight and alternating. Pinnate in one-half 
of calyx, in other half short and radiate. 
Well developed, primaries reaching center and curv 
ing some. Secondaries rudimentary. 
Numerous. Principal septum small and placed in 
fovea. 
Numerous. 
Numerous, thin, rising in pairs. Alternating, longer 
reaching center. 
Radiate, alternate, hroad. Generally angular towards 
the outer area. Primaries reach center. 
Radiate, alternate ; primaries reaching center. 
Radiate in the calyx ; each order extending into the 
columella. Each septum formed of two layers. 
One, which may he ob- 
scure or ohsolete. 
Radiate, alternate, 
structure. 
Primaries extend into central 
One, large and deep. 
Variously formed, equal or alternating. Primaries 
generally reach center. Thickened towards the 
wall. 
Well developed, 
growths. 
Side faces are supplied with thorny 
None indicated. 
Radiate, alternate. Primaries extend to near center, 
secondaries to pit with thickened extremities. 
Carina' sometimes occur. 
One, well marked. 
One, well marked. 
Well developed, alternating, lamellar; usually pro- 
longed over surface of tabulre to center as curved 
strife. 
Numerous, sub-equal or alternating. Primaries ex- 
tending only to central area. Delicate in outer 
vesicular zone. 
One, distinct, in form- of 
a narrow groove. 
Numerous, well developed, thick. Radiate in one- 
half of calyx, in other half pinnate to fovea. 
Variable in size, but 
usually well marked. 
One, little deepened. 
One, generally distinct. 
Well developed, alternate. Primaries extend to cen- 
tral area and give rise to curved plates which fold 
around columella and form the inner wall. 
Generally alternating in length and thickness. 
Septa extend from outer wall to center. 
Radiating and strong in the intermediate area, Rudi- 
mentary on the projecting surfaces of the cell cups. 
