J04 
SMITHSONIAN INSTITUTION 
scription and figure ; and he was entitled to amend the genus by setting out the other corre- 
lated characters which go with it. Thus there can be no reasonable doubt of the validity of 
the genus as of one or the other of the above dates. 
With the genus thus validated and recognized, it would seem that the family name 
Calceocrinidae proposed by Meek and Worthen in 1873, and adopted by De Loriol, Wachsmuth 
and Springer, Ringueberg, S. A. Miller, P. H. Carpenter and Bather, will have to stand. 
From these considerations it follows that the four stages of the family herein discussed 
are logically expressed by the following genera, the relations of which, in their broader aspects, 
may be thus summarized : 
Analysis of the Genera 
Radials 2 simple, 3 compound, connected with basals by muscular articulation instead 
of suture, admitting mobility of crown upon base as by a hinge, and 
consequent bending upon the stem to a pendent or recumbent posi- 
tion Calceocrinidae. 
Form A. Arm-bearing rays 4 (median and 3 lateral) ; stem at right of anal tube, 
and bilateral symmetry disturbed. lAx equal-faced ; arms heteroto- 
mous ; BB 4. Ordovician to Silurian Cremacriniis. 
All others. Arm-bearing rays 3 (median and 2 lateral) ; stem in plane of anal tube, 
and bilateral symmetry restored ; lAx unequal-faced. 
Form B. Lateral arms unequally dichotomous, with few branches; BB 4; Silu- 
rian Eucheirocrinus. 
C and D. Lateral arms heterotomous, branching numerously with axil-arm sys- 
tem from unequal-faced axillaries ; BB 3. 
Form C. R. post, and r. ant. inferradials separated by subanal piece; main 
branch of axil-arms may be hidden by outer ramule; segments of 
1 . ant. R usually separated ; fused basal usually triangular and narrower 
than hinge; median arm usually simple. Silurian Calccocrinits. 
Form D. Inferradials meet under anal v ; main branch of axil-arm always 
more or less visible ; segments of 1 . ant. R. always separated ; fused 
basal usually curved and about as wide as hinge ; median arm fre- 
quently branching. Devonian to Carboniferous Halysiocrinus. 
