306
P. H. CAEEENTEE ON THE EELATIONS OE
plate." An intermediate stage between the two is afforded by Homo-
crinus (fig. III. b), which differs from Dendrocrinus " only in having
the suture between the sections of the compound plate sloping
instead of horizontal. By this, in itself, trifling alteration, which
required no modification in the form or construction of other plates,
the lower portion of the original compound radial became trans-
formed into an anal plate." It is in fact " pushed slightly to the
rear, thereby becoming a regular anal plate or support for the
ventral sac"*.
"While entirely concurring in the views of Messrs. Wachsmuth
and Springer respecting the mutual relations of Hybocrinus, Homo-
crinus, and Dendrocrinus, I am not altogether in accordance with
them as to the relations of these three types to Iocrinus. They
have given us an interpretation f of the calyx of this type, which
differs considerably from that given by Hall and by Meek and
Worthen. I can offer no opinion upon this point

but, assuming
that their analysis of the Iocrinus- calyx is the right one (fig. III. c),
I cannot follow their comparison of it with Dendrocrinus. The
bifurcating plate, which gives rise both to the right posterior ray
and to the ventral tube, is regarded by them as a brachial with
interradial functions

and they refer to Dendrocrinus as illustrating
this point. As the plate in question is supported on the right
posterior radial, and is "of the same width as the other brachials,
and apparently similarly articulated," it is probably to be con-
sidered a modified brachial. But the lower half of the compound
radial of Dendrocrinus (fig. III. a), to which it is compared by
Fig. III. — Diagrams illustrating the Anal /System of the Cyatho-
crinida?. Copied from Wachsmuth and Springer.
y &h
%uu
r, Eadial. b. Basal.
A. Dendrocrinus.
C. Iocrinus (fide W. & S.).
Wo9Po
B
n. Underbasal. a. Anal system.
B. Tiomocrinus (emend., W. & S.).
"Wachsmuth and Springer, rests on two basal plates, and supports
the right posterior radial, which itself bears the brachials. There

Revision, pp. 66, 78. t Ibid. p.