280 
The American Geologist. 
May, 1891 
FOVE.E, 
1. One, well developed. 
Numerous; both orders reach columella. 
None. 
Reach center. Apparently in multiples of six, 12 at 
the base and 18 in the calyx. 
One, deep. 
Well developed, alternating; second order very short 
Completely developed. Numerous, closely placed. 
Smooth; consisting of three orders, the third very 
rudimentary. 
Both orders equally developed. Complete only near 
the base, raised folds above. 
Alternating. Primaries extend nearly to center, sec 
ondaries about half way. 
Alternating. Sides smooth, denticulate on inner edges 
10. None or very obscure. 
No lamellar septa, simply rows of spines. 
11. 
12. 
13. 
14. 
15. 
16. 
17. 
18. 
19. 
20. 
21. 
22. 
23. 
24. 
One, slightly devel- 
oped. 
Not regularly radiate, but inclined towards the 
stronger principal septa. Thick. 
One, well developed. 
Exsert, extending nearly to center. Rather regularly 
radiate. Secondaries rudimentary. 
One large and three 
smaller ones. 
Unequally developed and irregular. Pinnate to prin 
cipal septum. 
One is developed. 
Short, not reaching over half way to center. Alter- 
nating, secondaries marginal, somewhat inclined 
to primaries. 
One is indicated. 
Numerous, alternating, strong. Primaries nearly 
reach center. Side faces granulated. 
Spines instead of true septa. Sometimes united by 
sclerenchyma into more complete lamellae. 
One generally present 
and well character 
ized. 
Short, equal or alternating. May sometimes reach 
center as low ridges on the tabula?. 
One, lengthened and 
containing septum 
Numerous, unequal, irregularly arranged. Pinnate 
in one-half of calyx. 
Wanting. 
Radiate, alternate. Primaries do not reach center 
Secondaries one-half as long. 
Wanting or rudiment 
ary. 
Radiate, equal or alternate. Seen in calyx as broad- 
ening convex bands. Not sharply crested except 
near center. 
One on posterior side 
Obscure in type. 
Obscure or obsolescent. Fine, converging about the 
fovea : appear as mere ridges on the tabulae. 
None indicated. 
Radiate and alternate in type, primaries reaching 
nearly to center. Rudimentary in other species. 
Seemingly rudiment- 
ary. 
Radiate, alternate. Primaries extend to center. 
None indicated. 
Alternating, complete only in the tube-like channels. 
Primaries form a false columella. Extend outside 
as hands. 
