THE SANDSTONE OF FOSSIL RIDGE 189 
Ostrea patina M. and H. 
‘Rather common on Fossil Ridge from five to seven miles south of Ft. Collins. We 
have seen none elsewhere and find no other records for Colorado. Found in the Pierre 
of the upper Missouri River region (Meek). 
Ostrea pellucida M. and H. 
Rather common on Fossil Ridge. Not noticed in the Boulder District. Reported 
from the Mesa Verde formation, in La Plata Quadrangle. [Cross, Purington and Spencer, 
Folio 60, Geol. Atlas of the United States, supra, p. 5.) Found in the Fox Hills of the upper 
Missouri River region (Meek). 
Anomia retiformis Meek 
Abundant in the Hygiene sandstone from Lake Loveland to Rocky Ridge. Fossil 
Ridge is probably the type locality, which is described as a “‘ridge southeast of La Porte.” 
[Meek, Fortieth Parallel Survey, Vol. IV, Pt. I, p. 141.] Found occasionally above the 
Hygiene sandstone in the Boulder District. 
Volsella meekii E. and S. 
We found a number on Fossil Ridge from five to seven miles south of Ft. Collins. 
Not seen by us or recorded elsewhere in the state. Found on Yellowstone River in strata 
containing a blending of Pierre and Fox Hills species (Meek). 
Pholodomya subventricosa M. and H. 
We found one specimen five miles south of Ft. Collins on Fossil Ridge, and two at 
what is usually considered the upper limit of the Pierre southeast of Windsor. It is found 
in either the Eagle or Claggett formation (Stanton MSS, reported by Meek as Fox Hills) on 
the Judith River, Montana. 
Anatinau sp. 
Fossil Ridge, seven miles south of Ft. Collins, is the locality where we first found this 
shell. We also found one small specimen at the same horizon at Rocky Ridge, and 
several near the top of the Pierre as its limits are generally understood in Northern Colorado, 
southeast and southwest of Windsor. 
Thracia gracilis M. and H. 
We found several specimens on Fossil Ridge from five to seven miles south of Ft. 
Collins. We are aware of no other records or specimens from Colorado. It is found in 
the Claggett formation (Stanton MSS, reported by Meek as Fox Hills) near the mouth of 
Judith River, Montana. 
Nezra? sp. 
A single specimen not specifically identifiable but probably referable to this genus we 
found in the Fossil Ridge sandstone south of Ft. Collins. 
[Veniella humilis M. and H. 
The record of this species was based upon a cast of a single valve, which we have 
recently examined and find its identity not certain enough to warrant the retention of the 
record. The species is abundant at the top of the Pierre east of Fossil Ridge, southeast 
of Windsor.] 
[Lucina occidentalis Morton 
_ This record was based upon specimens so labelled in the University collections. An 
examination shows that they are Callista deweyi M. & H., a common Fossil Ridge species. 
However, this Lucina is found at about the same horizon at Boulder.] 
