SHUMARD— NEW PALAEOZOIC FOSSILS. 
113 
Uir 4 
El^acrinus Kirkwoodensis, n. sp. 
Body very small, subglobose, a little longer than wide, flat- 
tened above and below. Basal pieces very gently concave, 
with their edges on a level with the plane of the under side. 
Radial pieces (fork pieces) reaching to the base and occupy- 
ing more than four fifths the entire length of the body, narrow 
below and widest in the middle, sides gently arched. Interra- 
dial pieces subdeltoid, very prominent towards the apex, much 
longer than wide, obtusely angulated below, acutely angulated 
above, and notched on either side a short distance below the 
summit. Pseudo-ambul acral areas extending from base to 
summit, narrow, deeply impressed; sides nearly parallel; pore 
pieces amounting to about fifty in each field. A longitudinal 
fissure or slit extends from the central summit opening down- 
wards, separating the pore pieces of one side from' their fel- 
lows of the opposite for the distance of -about one fifth the 
length of the field, thence their inner edges are united in the 
median line rto the base. Pseudo-ambulaeral spaces lanceo- 
late^ sloping gently from their edges to the sutures. Ovarial 
apertures eight, very minute, situated at the notches of the 
interradial plates. Anal opening large, circular or very slight- 
ly elliptical. The surface markings are not plainly exhibited 
in any of the specimens I have collected of this species. On 
several of them I observe, more or less distinctly, irregular 
coarse rugae or pittings, which, however, may be due to weath- 
Dimensions. — Length, 0.20 of an inch; width, 0.18. 
The JElceacrinus Kirhwoodensis is nearly allied to JE, 
{Pentremitez) melo , from which it is distinguished by its 
much smaller size and less deeply excavated base. It also 
occupies a higher geological position. 
Occurs in the St. Louis Limestone (Carboniferous) on the 
Pacific railroad near Kirkwood, St. Louis county, Missouri. 
M 
cm 
2 3 4 5 6 7 
