IOWA ACADEMY OF SCIENCES. 
185 
Test spherical, with poles deeply impressed, ambulacra wide, 
narrowing above, composed of very short broad plates, about 
five in the space of one-tenth of an inch, each perforated by 
two small pores, four rows of pieces to each ambulacral area, 
and depressed in the median part of the field as to form a well 
defined meridional groove. Interambulacra in widest part com- 
posed of seven ranges of plates; each plate with a central 
tubercle. Spines slender, from one-half to three-fourths of an 
inch in length, with annulation at base. 
Horizon and locality. Devonian, Chemung sandstone: Dry den. 
New York. 
Vanuxem’s description is so meager as to hardly deserve 
mention. The above is essentially the same as that given by 
Hall. It is, however, far too imperfect, in the absence of 
figures, to allow with exactness very much to be known con- 
cerning the genetic relationships of the species. Ordinarily 
the form might be ignored entirely; but the importance of the 
type and its being the oldest echinoid yet known from Ameri- 
can ranks makes it desirable to recognize the form. Little is 
known of the species beyond the published notes of Hall, who 
states that “One specimen, as it occurs flattened upon the 
stone, is nearly two and three-fourths inches in diameter.” The 
specimen described by Mr. Vanuxem is upon a thin shaly sand- 
stone of about ten by eleven inches; one of the angles, being 
nearly one fourth of the area, having been broken off. Upon this 
slab is one specimen better preserved than the others, from 
which the characters have been mainly derived. There are 
three other individuals possessing the form and showing the 
ambulacral fields; while there are parts of four others with 
multitudes of slender spines scattered over the surface. 
Arch^ocodarts LEGRANDENSis Miller & Gurley. 
Arcliccocidaris legrcmdensis Miller & Gurley, 1890; Desc. New Sp. 
Fossils, p. 59. 
Horizon and localities. Carboniferous, Kinderhook limestone: 
LeGrand, Marshall county, Iowa. 
Archa:ocidaris agassizi Hall. 
Arcliccocidaris agassizi Hall, 1858; Geology Iowa, vol. I, p. 698, 
pi. xxvi, figs. la-d. 
.Arcliccocidaris agassizi Keyes, 1894; Missouri Geol. Sur., vol. IV, 
p. 127,, pi. XV, fig. 5. 
