HISTORICAL. 27 
clusion that by far the majority of the Neocrinoidea are built on the dicyclic 
plan, and either have small infrabasals, or had them in their larval state. 
We continued to use the term “vault” as opposed to disk, believing that 
the tegmen of Paleozoic Crinoids differed morphologically from the disk of 
later ones. Respecting the oral question our views had undergone consid- 
erable changes, owing to the discovery that the two smaller plates, which 
we supposed represented together the posterior oral, are radially disposed 
instead of interradially, and we inferred that the central plate alone repre- 
sented the oral pyramid of other Crinoids, a view afterwards strongly con- 
tested by Dr. P. H. Carpenter. 
In 1884 Carpenter’s Challenger Report on Stalked Crinoids came out, 
and in 1888 that on Comatule. In the former the author discussed among 
other things the morphological relations between Palaeozoic and Mesozoic 
forms, and replied to some points which we had brought out in the Revision. 
With regard to the structure of the tegmen he argued that some Platycri- 
nid had a “vault”; but that the ventral covering of others did not differ 
essentially from the disk of the Neocrinoidea. He believed that the Pal- 
wozoic Crinoids differed essentially from the later ones by means of their 
irregular symmetry, caused by the introduction of anal plates; and upon 
this and other grounds, to which we allude in another place, he made the 
Paleozoic and later Crinoids independent orders. In his classification he 
J 
fell back upon Leuckart’s almost forgotten name ‘‘Pelmatozoa,”’ which he 
made a branch of the Echinodermata, with Crinoidea, Blastoidea, and Cys- 
tidea as classes, and the Palwocrinoidea and Neocrinoidea as orders. He 
also discussed the oral question, adopting the view which we had brought 
out in 1881, but abandoned in the following year. He assumed that the 
so-called central plate represents the dorso-central at the abactinal side, 
the six proximals (his orals) the basals, and that the latter are homologous 
with the genitals of the Urchins. In the second Challenger Report, that 
on the Comatule, we were criticised very severely for asserting that prob- 
ably the Comatule had infrabasals in the larva, which were actually dis- 
covered by Bury before the Report was published. 
Among the many interesting papers written by Dr. P. H. Carpenter, 
none attracted more attention than the one in which he discussed the rela- 
tions of the basals in monocyclic and dicyclic Crinoids.* He proved that 
* On the “ Oral” and Apical Systems of Echinoderms (Quart. Journ. of Microse. Sci., 1878, pp. 351- 
383). 
