THE SANDSTONE OF FOSSIL RIDGE IgI 
Gyrodes sp. 
One example belonging to this genus but specifically undetermined was found at 
Fossil Ridge. It is distinct from either of the foregoing. 
Anchura haydeni White 
Fossil Ridge is the type locality of this fine species. A specimen has been reported 
at Boulder [Univ. Colo. Studies, Vol. II, p. 101], but the specimen is not now to be found 
and it is believed to be a case of mistaken identity. We are not aware of its occurrence 
anywhere else and it is not common at Fossil Ridge. 
Anchura americana E. and S. 
We obtained two specimens at Fossil Ridge, two above the Hygiene sandstone at the 
brick kiln east of University Campus, Boulder, and one at the same horizon above the 
Hygiene four miles north of Boulder, In the Denver Basin monograph it is credited to 
the middle Pierre and lower Fox Hills. In the upper Missouri region it is found in strata 
containing a blending of Pierre and Fox Hills species (Meek). 
Fasciolaria ? sp. 
Casts belonging apparently to this genus have been found at Fossil Ridge from five 
to seven miles south of Ft. Collins. A small example of F. ¢ulbertsoni, usually con- 
sidered a Fox Hills species, was found below Hygiene sandstone southwest of Berthoud. 
Volutoderma n. sp. 
The only locality in which we have found this species is Fossil Ridge, seven miles 
south of Ft. Collins, and only two specimens found there. 
Haminea? sp. 
Where Fossil Creek crosses Fossil Ridge we found a specimen somewhat doubtfully 
referred to this genus and specifically undetermined. It has the appearance of H. sub- 
cylindrica M. and H. 
Anisomyon borealis Morton 
A few found at Fossil Ridge. It is reported from a horizon somewhat above the 
Hygiene sandstone north of Boulder (Stanton), and from the base of the Pierre in the upper 
Missouri region (Meek). 
Anisomyon centrale Meek 
We found eight or ten on Fossil Ridge. It is not clear from the literature just what 
horizon it occupies in other localities. 
Anisomyon patelliformis M. and H. 
We have found a dozen at Fossil Ridge, none exceeding an inch in length. There 
is some doubt as to the validity of some of the nominal western species closely related 
to this one. With our specimens the narrower outline and more nearly central apex of 
the juveniles, as indicated by the lines of growth and by one immature specimen, point to 
subovatus, but in the angle of apical convergence and small size they are as patelliformis. 
On the Yellowstone river it is found in strata containing a blending of upper Pierre and 
Fox Hills species (Meek). 
CEPHALOPODA 
Nautilus dekayi Morton 
We found one specimen at Fossil Ridge and Professor D. W. Spangler has presented 
another from the same place. We also have one from above the Hygiene sandstone three 
