152 MESOZOIC AND CENOZOIC ECHINODEEMATA OF THE UNITED STATES. 



Merriam says: "Numerous large spines much like those of Schizaster have been found at 

 one locality, but if they belong to this genus at all they were probably derived from another and 

 much larger species." 



Locality. — Contra Costa County, Cal. 



Geologic horizon. — Martinez and Tejon formations, Eocene. 



Collection. — University of California. 



Schizaster armiger Clark, n. sp. 

 Plate LXX, figures la-d. 



Determinative characters. — Test rather large, cordiform, depressed upper surface slopes at 

 first rapidly then more slowly from anterior margin to apical system, beyond which an elevated 

 sharp ridge continues to the truncated posterior margin. Ambulacra in broad deep furrows, 

 the paired ambulacra in moderately sunken petals, the anterolateral being about one and one- 

 half times as long as the posterolateral. Peripetalous and lateral fascioles distinct. 



Dimensions. — Length 53 millimeters; width 46 millimeters; height 22 millimeters. 



Description. — This species has a test of moderately large size, much depressed and clearly 

 cordiform in marginal outline. The upper surface slopes at first rapidly from a sharp anterior 

 margin to near the apical system when it becomes nearly flat for a short distance. Beyond 

 the apical system a sharp elevated ridge highest near the middle point continuous on to the 

 truncated posterior margin. 



The ambulacra are broad, the single anterior ambulacrum being situated in a deep broad 

 groove that deeply indents the anterior margin. The paired ambulacra have broad deep petals, 

 the anterolateral being somewhat over one and a half times as long as the posterolateral. 



The interambulacra are more or less flat, slightly gibbous, the posterior much elevated 

 forming a sharp ridge. The surface is thickly covered with small perforate tubercles. The 

 peripetalous and lateral fascioles are very distinct. 



The peristome is near the anterior margin in a shallow depression. The periproct is high 

 on truncated posterior margin. 



Locality. — Cocoa post office, Choctaw County, Ala. 



Geologic horizon. — St. Stephens limestone (lower part), upper Eocene. 



Collection. — U. S. National Museum (141104). 



Schizaster sp. 

 Plate LXX, figure 2. 

 Fragment of spatangoid test, Clark, 1901, Maryland Geol. Survey, Eocene, p. 232, PL LXI, fig. 1. 



Description. — A fragment of a spatangoid test found among the Eocene materials collected 

 at Evergreen, Va., apparently belongs to the genus Schizaster, to which it is here referred. A 

 portion of an ambulacrum with the adjacent portion of an interambulacrum, showing many 

 characteristic features, is preserved. The ambulacrum, probably one of the anterolateral pair, 

 is petaloidal, the petal sunken and rather narrow. The interambulacrum is somewhat gibbous 

 and has preserved a part of a peripetalous fasciole. 



Locality. — Evergreen, Va. 



Geologic horizon. — Nanjemoy formation, middle Eocene. 



Collection. — Johns Hopkins University (T 2001). 



Genus LINTHIA Merian. 



Linthia wilmingtonensis Clark, n. sp. 



Plate LXX, figures 3a-c. 



Determinative characters. — Test large, cordiform, gibbous above, nearly flat below, ambu- 

 lacra wide, anterior in deep groove, anterolateral with petals in long deep grooves, postero- 

 lateral wi.th petals about one-half the length of the anterolateral and also deeply sunken. Inter- 



