Agelacrinidae and Lepadocystinae 
427 
No definite ornamentation was noted on the surface of the 
plates of Streptaster. 
In Thresherodiscus, there may have been minute granules on the 
surface of the larger interambulacral plates, but in the present 
weathered condition of the plates this can not be determined 
definitely. 
I have seen nothing to suggest the presence of distinct and 
readily recognizable granules on any Ordovician species referred 
to Agelacrinus or Lepidodiscus. Such granules as occur on these 
species appear to belong to species of Dermato stroma, covering the 
surface of the Agelacrinus with a very thin, granule-bearing layer 
(plate I, Fig. 3B; plate III, Figs. 1, 4). 
27. The Central or Substomial Cavity of 
Agelacrinus Pileus 
In 1892, Miller and Faber described the lower side of the upper 
face of a theca of Agelacrinus pileus from near the top of the hills 
at Cincinnati, Ohio. The horizon probably was in the Corryville 
member of the Maysville. The specimen forms No. 8825 in the 
Faber Collection in Walker Museum, at Chicago University. In 
this description (Journal of Cincinnati Society of Natural History, 
vol. XV, p. 85, plate I, Fig. 10; see also plate I, Fig. 5A, and 
plate II, Fig. 4 of this Bulletin), the following remarks refer to 
the substomial chamber, as seen from below Explanatory com- 
ments are added by the writer in brackets. 
The coverings of the rays (the floor plates, as seen from below) are 
united near the center of the fossil by a subpentagonal rim, that extends 
deeper into the visceral cavity than any part of the internal (part of the) 
rays, and, we believe, extended to the very bottom of the test, and formed 
the part of the organism that adhered to the foreign object to which 
these animals attached. Three sides (the anterior sides) of this project- 
ing rim are preserved and shown in the illustration, and the surface is 
flattened, as if for the purpose of attachment. Within this pentagonal 
rim there is a pit showing the five subovate mouths of the ambulacral 
canals, which are also indicated in the illustration. 
Miller and Faber did not overestimate the value of this specimen 
since it is still the best specimen for showing the lower surface of 
the upper face of the theca. It needs, however, a much fuller 
description, and such a description is attempted here. 
