70 THE CRINOIDEA CAMERATA OF NORTH AMERICA. 
in the calyx, were treated by us in the same way as the Camerata. Schultze, 
however, described Yazocrinus as having but one radial, in which he was 
correct from his standpoint, for the succeeding plates seem to be united 
among themselves, and with the radials by loose suture or a sort of rudimen- 
tary articulation. Carpenter described Pextacrimus and the Comatule, which 
are in a similar condition to the Ichthyocrinide, as having three radials in 
all cases, whether the plates are enclosed by perisome or not, and he distin- 
guished the rami as primary, secondary, and tertiary arms. According to 
him, Phizocrinus Rawsoni, with ten arms, has three radials; while 2. lofotensis, 
like Cupressocrinus, Pisocrinus, and all Crmoids with but five arms, have one 
radial, followed by brachials. He thus made the second plate of the ray a 
second radial in the former, and a frst brachial in the latter, giving to parts 
which are undoubtedly homologous different appellations, while distinct parts 
were thrown together. The methods of treating these plates heretofore 
adopted were not only empirical, but inconsistent with the principles of 
morphology; and the want of uniformity among the different writers, 
respecting the terms, must have been perplexing to the student when con- 
sulting their works. 
In 1881,* and again in 1885,f we expressed the opinion that the arms 
fundamentally begin with the second plate of the ray, and that all Crinoids 
have but one ring of radials. In support of this we stated that only the 
lower ring could be homologized with the oculars of other Echinoderms ; 
that in the simpler form—the Inadunata—the arms were free from the 
(first) radials, and that in the remaining groups the lower arm plates were 
incorporated gradually in paleontological time. We refrained, however, at 
that time from changing the terminology, finding it convenient for purposes 
of description to continue the old terms. 
Our interpretation of the plates was accepted by Carpenter in 1884,+ 
who confirmed it by the developmental history of the plates. The “ outer 
radials,” he says, “ commence as imperfect rings, which soon become filled up 
with lengthening fasciculated tissue, just as is the case with the stem joints 
and later brachials;”’ but “the jst radials, like the basals and orals, com- 
mence as expanded cribiform films.” He further alluded to the fact that the 
so-called primary radials of Mefacrinus are pinnule-bearing, —a thing which 
we have observed in exceptional cases among the Poteriocrinidx also. 
* Revision, Part IL., p. 10. + Ibid, Part IIT.p. 12. 
{ Challenger Rep. on the Stalked Crinoids, p. 48. 
