258 F. B. Meek—Two new Star-jishes, 
the articulation of a spine, measuring from 0-16 to 0-28 inch 
in length, and about 0°04 inch in thickness, and consequently, 
distinctly larger than those of the dorsal side. e l 
side, the so-called madreporiform body can be seen near the 
margin of the disc, in one of the axils between two of the 
ranges. Itis nearly flat, of a transversely suboval or subtri- 
lobate form, the lobed side being directed inward; while the 
little divisions are seen radiating and bifurcating inward on the 
middle lobe, and laterally on the lateral ones, like the nerves 
of the pinules in some kinds of ferns. 
From some of the characters imperfectly seen in the species, 
it is possible that better specimens may show it to belong to the 
genus /’etraster, and render it necessary to write its name Petras- 
ter Dyer. The structure of the dorsal side of Petraster is, I 
believe, not certainly known. In the published species of 
Palcaster, the dorsal pieces are illustrated as if close-fitting, or 
at least without very obvious pores passing between the pieces 
Indeed, it was originally supposed that the dorsal pores passed 
through these pieces, instead of through the sutures between 
them, and this was mentioned in the generic description as one 
of its most important characters. I have no typical examples 
of that genus at hand, showing the dorsal side; but as no such 
characters are shown in the figures of any of the published 
species, or alluded to in connection with the genus, in later 
publications, we may perhaps infer that it would not now be 
1nsisted upon as an essential character of the genus. Bogs 
Locality and position Cincinnati group of the lower Silurian; 
from the horizon of about one hundred feet below the tops of 
the hills at Cincinnati, Ohio; where it was discovered by Mr. 
C. B. Dyer, to whom I have dedicated the species. 
STENASTER GRANDIS Meek. 
Attaining a very large size, with the body or dise compara- 
tively sane, or oaig oP che breadth of the anitad inner ends of 
the five rays. Rays long, slender, gradually tapering, and very 
flexible, widest at their immediate connection with the body, 
tubercles, or sométimes assume almost the character of short 
spinules, and are arranged in quincunx, so as to form about 
eight rows near the middle of the rays; those of the outer two 
rows being a little larger than the others. Dorsal pores ap 
parently rather large, and passing through between the concavé 
sides of contiguous pieces. Ventral side of body unknown. 
that of the rays composed of the usual single row of jie 
verse adambulacral pieces on each side of the well defined, 
