260 Wachsmuth and Springer—Silurian Crinovds. 
reason to appreciate, not only from his published works, but 
from an extended correspondence with one of the writers 
during the preparation of his admirable articles on the struc- 
ture of Crinoidea, Cystidea and Blastoidea, in 1869. 
Billings established his genus Reteocrinus upon two species, 
R. stellaris and &. fimbriatus, which are described in Decade iv, 
of the Geol. Surv. of Canada, pp. 64 and 65, and illustrated on 
pl. ix, figs. 8,4. Of &. stellaris, which he took for the type 
of the genus, he had four specimens, three of which were frag- 
mentary, and all of them in such a poor state of preservation, 
that Billings himself says at the end of the description, that 
“‘none of the specimens collected are perfect, and the characters 
of the species, therefore, have not been fully ascertained.” 
The interradial spaces were very deeply depressed and filled 
with a hard matrix of limestone, which concealed from vieW 
the whole interradial portion of the calyx, with the exception 
of some small stellate points, which are now known to be the 
projecting summits of the plates. His principal specimen, fig. 
4a, was so imperfect that Billings seemed to think that the 
ridge-like series of anal plates on the azygous side might possi 
bly be an arm, and that there might be six (primary) arms 10 
the species, although the generic description calls for but five 
primary radials. He considered the plates following the first 
rimary radials to constitute arms, and found that the right 
(left posterior) of these ‘‘arms” divided on the fourth joint, 
but the others he could not see distinctly. The genus, 0 
which this was the best specimen of the typical species, he con- 
sidered to have “no perfectly formed plates,” and its cup to 
consist of a “reticulated skeleton, composed of rudimentary 
lates, each consisting of a central nucleus, from which radiate 
from three to five stout processes,” (Dec. iv, p. 63), characters 
which do not exist, as subsequent investigation of the type 
specimen has fully demonstrated. : 
R. fimbriatus, the second species, was described from a single 
imen, Dec. iv, pl. 9, fig. 8a, and this, as Billings states, 18 
“very imperfect.” There is enough, however, in his figure 
and description to show, that in the opinion of the founder of 
the genus, a species having a pentagonal column; the “ basals | 
(underbasals of our terminology) minute; the “ subradials 
(basals) one line in height; the arms several times divided (but 
only once in the body); a bifurcation on the third primary 
radial; and the spaces between the rays ‘‘ filled with very small 
” might properly be referred to Reteocrinus. These char- 
acters apply mar well, and with scarcely any variation, to 
the so-called Glyptocrinus O’Nealli Hall, G. cognatus Miller, 
Gi. Boeri Meek, and. Reteccrinus gracilis Wetherby, and with 
the exception of the column, to Gl. Richardsoni Wetherby, Gl. 
S 
&. 
