102 
Kirtley F. Mather 
quite abundant, have been found associated at only one local- 
ity, Station 301. With the exception of that occurrence, 
P. angmtus is not represented in any of the Oklahoma collections 
while in the material upon which these studies are based P. 
riisticus has not been observed in any of the collections from 
Arkansas. Hambach, however, described both species as occur- 
ring in Washington County, Arkansas. Probably the fact is 
that P. angustus was rarejn the western part and P. rusticus 
was rare in the eastern part of the Morrow basin. Hambach^s 
reference to the “Chester limestone’" is, of course, to the lime- 
stone of the Morrow group. 
Horizon and locality. Brentwood limestone: Sawney Hollow, 
Oklahoma (Station 210). Morrow formation: near Choteau 
(Stations 307 and ?298), Ft. Gibson (Station 301), and Gore 
(Station 305), Oklahoma. 
CRINOIDEA 
POTERIOCRINID^ 
Genus HYDREIONOCRINUS De Koninck 
Hydreionocrinus sp. 
Plate II, figures 5-6 a. 
A number of the spatulate spinous plates which surround the 
summit of the ventral sac of the crinoids referred to this genus 
are in the Morrow collections. Nothing is known as to the 
other parts of these forms and therefore their specific relation- 
ships cannot be suggested. 
Horizon and locality. Brentwood limestone: near Fayette- 
ville, Arkansas (Stations 147 and 152). Morrow formation: 
near Ft. Gibson, Oklahoma (Stations 296 and 301). 
Genus CROMYOCRINUS Trautschold 
Cromyocrinus grandis n. sp. 
Plate III, figures 2, 2a; text figure 1. 
Description. Dorsal cup large and globose, its height equal 
to about five-eighths its diameter, base convex, the column attach- 
ment a crater-like depression surrounded by an elevated ridge, 
the upper portion of the cup constricted with the greatest 
diameter occurring at about the middle of its height ; infrabasals 
