SWALLOW AND HAWN—THE ROCKS OF KANSAS. 183 
beak and closes the aperture; in front of the cardinal cae mee 
isa flat, narrow area. Both valves are gree nted 
lar, indistinct, concentric corrugations or lines ose 
be 7 assume the form of thin; scaly ranean = — 
margin ; 
ous seme unequal, depressed tubular pines are Lasleivn on 
all parts of the surface, even to the point of the beak; their 
attachments make the shell appear as if marked with ‘small, 
rounded, interrupted, longitudinal cost; they are smaller on 
ventral valve. In some specimens there are indications of 
an effort to range them in concentric lines, particularly near 
the ; but usually there is no perceptible order, which 
together with the narrow area of the dorsal valve, and other 
characters, gives the shell strong ae with the Productus 
horrescens of Verneuil. 
ou of dorsal valve, 1.08; greatest width, 1.11; height, 
0.55; length of cardinal line, 0.87; length of ventral valve, 
0.91; a, 1 07. 
from the P. 5 ata WV. & P, which it faintly resembles, by 
as want of large concentric ridges, and by the smaller size 
: Sg eaam eH and irregular arrangement of is pai 
| The § ia Morrissiana, King, has a larger 
Pay Hawn’s collection from the Lower pein! » Rocks, 
in in he rly of ees a a where it was associated 
on. cert at the bey de e 
the center, and i in a cir : _ to the | 
