64 THE CRINOIDEA CAMERATA OF NORTH AMERICA. 
299, we asserted that not only the majority of Stalked Crinoids, but also the 
Comatulx, were built upon the dicyclic plan, and probably had infrabasals 
in their larval state. 
The centro-dorsal at the Pentacrinoid stage of the Comatule, as may be 
seen by examining Plate VI. Figs. 18 and 19, agrees closely with that of the 
Apiocrinid. It is interradially disposed at the proximal face, and also at 
the distal face, so that its angles correspond with the angles of the basals, as 
in those dicyclie Crinoids whose infrabasals are hidden by the column; and 
even in its free floating stage the centro-dorsal retains its interradial 
position. 
So strongly were we impressed with the conviction that the Comatule 
are dicyclic Crinoids,— although no traces of infrabasals had ever been 
found by Wyville Thomson, the two Carpenters, Goette, and others who had 
extensively studied the embryology of Antedon, — that we urged European 
investigators to make fresh search for these plates. 
It was therefore with no little satisfaction that we learned from Dr. 
Carpenter in July, 1887, that infrabasals, whose existence we had predicated 
upon paleontological evidence, had actually been found by Mr. H. Bury. 
This important discovery was announced at the Manchester meeting of the 
British Association, and communicated by Mr. Bury in a paper on “ The 
early stages in the Development of Axtedon rosacea.’ * The plates appear in 
the ciliated larva, and consist of three unequal pieces, which in the Penta- 
crinoid stage are fused together with the top-stem-joint (centro-dorsal), so as 
to form together with the latter one large plate, with five angles, radial in 
position. One of the plates is smaller, and has but one salient angle, the two 
larger ones having two, —a structure which suggests that the two latter may 
represent a pair of anchylosed plates. Three similar plates, but with a some- 
what different orientation, persist throughout life in the Ichthyocrinidx, but 
the smaller plate of Antedon rosacea, if we understand Mr. Bury, is placed 
anteriorly ; while that of the Ichthyocrinidx is directed posteriorly (Table 
A, Figs. 14 and 15).t 
It is of considerable importance that the infrabasals of all Carboniferous 
Ichthyocrinide are coalesced with the top-stem-joint (centro-dorsal) similar 
to those of Antedon. In specimens in which the column has been detached 
from the crown, the small infrabasals generally adhere to the top-stem-joint 
* Philosophical Transactions of the Royal Society of London, 1888, pp. 257-300. 
+ The orientation of this plate was incorrectly given by us in the Revision, Part III. Plate 6, Fig. 23. 
Since then we have found out that it is located in all Ichthyocrinide to the right of the posterior basal. 
