2o8 Bulletin of Laboratories of Denison University [Voi. xi. 
county permits us to add a few details to the original description. 
Our specimens are mostly in the form of casts of the inte- 
rior derived from the septaria concretions of the so-called ceph- 
alopod zone which seems to lie near the base or perhaps below 
the base of the Fox Hills division. 
The texture of the shell, where preserved, is lamellar and 
prismatic, the inner nacreous layer being frequently preserved. 
Strong lines of growth lie parallel to the anterior margin, which 
is more nearly straight than the posterior, but turn by rather an 
abrupt flexure, parallel to the curved free margin to an oblique 
union with the lateral carina. 
The strongly curved posterior margin is joined abruptly by 
the free posterior lip, which is strongly arched rather than 
straight as represented by White. The striae of the posterior 
portion of the shell are parallel to the outline of the lip. The 
radiating striae are relatively inconspicuous and the beak is more 
abruptly acute than represented by White. 
Legumen (?) appressinn^ Conrad. 
Shell transversely elliptical, over twice as long as high ; 
valves depressed, thin ; shell narrowed anteriorly and acute at 
the anterior extremity ; posterior end broader but sharply 
rounded at the middle of its height ; hinge line long; ligament 
groove long and deep ; surface marked with fine even concentric 
striae. 
We at first considered this a new species but it may more 
probably be identical with the one quoted. Upper sandy layers 
above lignite in Rio Puerco valley. 
Liopistha concenhica, Stanton. 
Plate XXXIII, Fig. 5. 
(Including L. elongata, Stanton.) 
A number of specimens from the gasteropod zone in the 
Rio Puerco valley resemble L. concentrica closely but they are 
mingled with others of somewhat larger size that have the out- 
line of L. elongata. These large ones, however, have the con- 
centric markings as well developed as the smaller and some of 
