THYSANOCRINIDAD W. and Sp. 
(GLYPTASTERID W. and Sp. 1885). 
Dicyciic. LOWER BRACHIALS AND INTERBRACHIALS FORMING AN IMPORTANT PART OF 
THE DORSAL CUP; INTERBRACHIALS WELL DEFINED. RADIALS IN CONTACT EXCEPT 
AT THE POSTERIOR SIDE, WHERE THEY ARE SEPARATED BY AN ANAL PLATE. 
Analysis of the Genera. 
Infrabasals 5. 
A. ANAL SIDE SLIGHTLY ELEVATED. ANUS WITHOUT A TUBE, 
1. First anal plate followed by three plates. 
a. Dorsal cup deep. 
ZATMS UNISeLI al, oO Nee rn une tone n nnn TV.GHOGRUNTESS 
Arms biserial, erect, ten totwenty . . . . . . . . THYSANOCRINUS. 
b. Dorsal cup short, almost flat. 
Arms pendent, posterior oral and radial dome plates 
SOMME, 5 5 9 5 6 S ody Ss Hypriocrinus. 
2. All interbrachial spaces having a single large plate . . . . Iprocrinvs. 
B. ANAL SIDE BULGING. ANUS AT THE END OF A TUBE, 
1. First anal plate followed by three small plates. 
Rays produced into tubular extensions. 
Infrabasals large Sa A eee 
2. First anal plate followed by three large plates. 
Rays branching in the regular way. 
Infrabasals'small= . = = = = - 
- . . + . UAMPTEROCRINUS. 
Praca Sot SUL Pee SIPHONOCRINUS. 
Geological and Geographical Distribution. 
Number of known species. 
(Open figures indicate American, those marked ( ), European.) 
Formation. THYSANOCRINID2®. 
| = aa 
: Ke 
n 
5 5 a EI 2 
A f=} a =) B a 
sive iS a f= . o 
; pproximate = S I 2 2 B 
General. American. European 3) S 8 q 5 S 
Equivalents. a 3s 12 = a, 3 
2 = 24 5 5 S 
> a b> = 3 ey 
| H q i =| a) 
ae Dudle = 
% Upper i y > (7 1 4 1 3 
5 f PP Niagara. Gotland. 5 (7) 
2) ie eee ot eT rn a 
5 Lower} Huds. River. 2 | 
Total species . . . 23 aon fe 
