PLATYCRINIDZ. 645 
Geological and Geographical Distribution. 
Number of known species. 
(Open figures indicate American ; those marked ( ), European). 
FORMATION. ; PLATYCRINIDA. | 
vs | 
= ees 2 = A : 3 A : 
S merican. 2 2 H or S a 4 i | 
( rt | 
& B-5 So er one ae ele eee | 
ag 5 "3 5 5 e ts = 
4 'S) Ss) S) = Ay ee 
St. Louis. Dy 
Warsaw. 1 
: ees sR See l eoe  an ese 
S) Keokuk. 4 
D 
So ————————— 
= 
(o) . 
= Upper Burlington. a 5 14 6 
fas} fas) 
E 23 -4—|—_ + +e +— 
Ri . 5 
Lower Burlington. S.5 28 
Kinderhook. 
Waverly. 10 
Chouteau. 
A Hamilton. 1 
‘gl Eifel. (1) 
=o 
f 1 
A Lower Helderberg. Grauwacke. | (1) 2 i 
Pa a | as es | 
Ste Wenlock 
as : EA 
oe Niagara. Coen 1 (2) | 8(5) 
4. 60 6 
73 1 2 
Movalisweciess <2 sae 108 } (35) (1) (1) (2) (5) | (26) 
