438 
Aug. F. Foerste 
plates of the left primary ambulacral ray may be traced on the 
anterior side, in a proximal direction, as far as the first lateral 
covering plate at the proximal end of the anterior ray, while on 
the posterior side of this left primary ray they may be traced to 
a point on the posterior side of the mouth, opposite the median 
line of the anterior ray. These lateral covering plates show no 
enlargement along the oral slit, so that it is regarded as very prob- 
able that the peristomial plates did not differ conspicuously in 
size from the adjoining lateral covering plates, as is the case in 
Agelacrinus pileus, and to some extent also in A. cincinnatiensis, 
and probably also in other Ordovician species referred to Agela- 
crinus or Lepidodiscus. 
Beyond the extremities of the remote branches of the ambulacral 
rays, there is a marginal or peripheral zone of imbricating squam- 
ose plates resembling those of the inner band of the peripheral 
ring of other Agelacrinidae. Only the proximal ends of these 
plates are well exposed, but these are sufficiently extended later- 
ally to indicate that their general form is short but broad. In a 
proximal direction these marginal plates are successively larger in 
size, merging gradually into the series of large central interambu- 
lacral plates. In a distal direction, on the posterior border, the 
marginal plates of the peripheral ring become successively shorter 
and more numerous, and resemble the marginal plates of Lepido- 
discus cincinnatiensis, as illustrated by Hall, in Figure 7 on plate 
6, of the Twenty-fourth Annual Report of the New York State 
Museum. They are ornamented by short parallel vertical ridges 
or elongated granules. On the anterior border, there is a series 
of narrow, but elongate imbricating plates, resembling the narrow 
imbricating scales of the cup at the base of an acorn, or the plates 
at the base of the margin of Streptaster vorticellatus, as illustrated 
by Hall in Figure 12 of the plate cited above. There is no means, 
at present, of accounting for these differences in appearance of the 
smaller plates along different parts of the border. Of the larger 
plates, forming the inner band of the peripheral ring, there appear 
to be about six rows, counting in a diagonal direction, beneath 
which, along the anterior margin, there are three or four rows of the 
smaller narrow plates. Along the posterior border, there are five 
or six lowdr rows of smaller plates, but these are laterally elongated 
as in the case of the overlying rows of larger sized peripheral plates. 
No surface ornamentation was detected upon any of the larger 
