138 ECHINODERMATA—PELMATOZOA SUB-KINGDOM IIT 
disthals and interpalmars often, and in most cases anals also present. Arms 
uniserial or biserial, and pinnulate. Ordovician to Carboniferous. 
[Analysis of Families, according to Wachsmuth and Springer.! 
if 
Lower brachials and interbrachials forming an important part of the dorsal 
oO 
cup. 
A.—INTERRADIALS I[tt-DEFINED. 
The lower plates of the rays more or less completely separated from those of other 
rays, and from the primary interradials, by irregular supplementary pieces. Anal 
interradius divided by a row of conspicuous plates. Dicyclic or monocyclic.— 
RETEOCRINIDAE. 
B.—INTERRADIALS WELL-DEFINED, 
1. Dicyclic— 
(a) Radials in contact except at the posterior side. —THYsSANOCRINIDAE. 
(6) Radials separated all arownd.—RHODOCRINIDAE, 
2. Monocyclic— 
(a) Radials tr contact all around. 
Symmetry of the dorsal eup, if not strictly pentamerous, disturbed by the introduction 
of anals between the brachials only. —MELOCRINIDAE. 
Arms borne in compartments formed by partitions attached to the tegmen. Dorsal cup 
perfectly pentamerous. Calyx plates limited to a definite number.—CALYPTOCRINIDAE. 
b) Radials in contact except at the posterior side, where they are separated by an anal plate. 
L 4 ’ q ‘L f 
First anal plate heptagonal, followed by a second between two interbrachials.—BatTo- 
CRINIDAE. 
First anal plate hexagonal, followed by two interbrachials without a second anal. Arms 
branching from two main trunks by alternate bifurcation. —ACTINOCRINIDAE. 
itt 
Brachials and interbrachials but slightly represented in the dorsal cup. 
ey) 
1. Dicyclice— 
Radials in contact except at the posterior side——CROTALOCRINIDAE. 
2. Monocyclic— 
(a) Radials in contact all around. Base pentagonal. —PLATYCRINIDAE. 
(b) Radials separated at the posterior side by an anal plate. Base hexagonal. 
Basals followed directly by the radials —HExACRINIDAE. 
Basals separated from radials by accessory pieces. —ACROCRINIDAE. | 
Family 1. Platycrinidae. Roemer. 
Dorsal cup composed of a monocyclic base and a circlet of five large vadials, 
without special anal plate. The lower brachials, which form part of the calyx, similar 
in form and size to the free arm-joints.  Interradials heavy, restricted almost 
exclusively to the tegmen ; only those of the first row to a certain extent interbrachial. 
Arms often numerous, generally free from the distichals upwards; uniserial or 
biserial. Pinnules well developed. Silurian to Carboniferous. 
' [Wachsmuth, C., and Springer, F. The Crinoidea Camerata of North America (Memoirs 
Museum Comp. Zool. vol. xxiv.) In press. The above is extracted from proof-sheets kindly 
furnished by the authors. —TRrans. ] 
