Agelacrinidae and Lejpadocystinae 
417 
The floor plates of Agelacrinites heecheri (plate I, Fig. 2). 
from the lower Carbonic (Clean conglomerate) of Warren, Penn- 
sylvania, are figured by Clarke {New Agelacrinites, 1901, p. 195, 
Fig. 6) as also arranged in a single row, the plates overlapping 
each other distally, as seen from below. 
19. Floor Plates of Ordovician Species Referred to 
Agelacrinus 
Meek, in describing Agelacrinities cincinnatiensis {Ohio Paleon- 
tology, vol. i, p. 55, in 1873) refers to a specimen, a little more than 
an inch in diameter, found by L. B. Case at Richmond, Indiana, in 
the upper part of the Richmond group. Judging from the horizon, 
this specimen may have belonged to Agelacrinus faheri, which was 
described from the same locality and horizon. Regarding this 
specimen Meek stated : ‘^The inner side of each arm or ray is here 
seen to be composed of a single series of quadrangular pieces that 
are not imbricating.’’ 
Miller and Faber, in describing the lower surface of the upper side 
of the theca of a species of Agelacrinus, identified as Agelacrinus 
pileus {Journal of Cincinnati Society of Natural History, vol. xv, p. 
85, plate I, Fig. 10, in 1892; see also plate I, Fig. 5Aand plate II, 
Fig. 4 in this Bulletin), made the following statements, to which 
are added, in brackets, such explanatory terms as are deemed 
necessary for a ready understanding of the descriptions given. 
The under side of the rays, as seen from below, consist of a row of 
plates on each side of the furrow (the covering plates), which interlock 
at the bottom of the furrow (as seen from below), and are, therefore, with- 
out reference to abutting (interambulacral) imbricating plates, pentag- 
onal instead of quadrangular, as Meek described them. (Meek de- 
scribed the floor plates as quadrangular, while Miller and Faber had the 
covering plates in mind when they described the latter as pentagonal.) 
They (the bases of the covering plates) extend beyond the margin of the 
(interambulacral) imbricating plates into the visceral cavity (for a dis- 
tance equal to) half the depth of the ambulacral furrows (as seen from 
below), and are separated from each other, in their extensions laterally 
into the visceral cavity, so as to present a strongly serrated edge, as 
shown in the illustration (loc. cit., plate I, Fig. 10; see also plate 1. 
Fig. 5 A of this Bulletin) . The furrows (as seen from below) are covered 
with thin nonimbricating plates (floor plates), that do not cover the 
serrated edges above described. Part of the covering (consisting of the 
floor plates) is preserved in our specimen as shown in the illustration, on 
two rays (anterior and left rays), but the plates are so small and the 
