LOWER CRETACEOUS DEPOSITS CALIFORNIA AND OREGON

123 3WJWEH CRETACEOUS DEPOSITS IN CALIFORNIA AND OREGON
Pholadomya rutietft Anderson, n. sp.
(Flats i, fliUTM 3, t)
Shell of medium size, robust, oval in outline, umbones eLcvatad, anterior; beaks
incurved, approximate, cxc&vsted before and behind;posterior dorsal margin sloping
gently, rounded uniformly to the rounded posterior end; anterior end more broadly
rounded to the basal border; surface marked by somewhat regularly concentric
ridges, which become fainter on the poateror quarter of the shell; faint plications
visible on the anterior end below the boats; section of shall near the umbones cordate
; posterior end thin, section narrow,
The holotype (Calif. Acad. Sci., type Coll.) was found by R. Dana Russell at
Locality 1659 (Calif. Acad. Sci.) in tbe Neptune zone an Hulen Creek, Shasta County.
It has the following measurements: length, S3 mm.; height, 46 nun,; greatest thickness
of both, valves, 38 mm.
Six fairly well preserved examples of the species were obtancd hers, associated
with, Pmnsia tubquadrata (Anderson), Beudanticerat breweri (Gabb), Lytocrrat
dumlifcrtne, nov., DouBilleietras mannmllalum var., and other species. The horizon
of this species is about 450 feet beneath the local top of the Hulen beds, and about the
same distance above that of the preceding ej^ties.
Pholadermya aliumbanaia Anderson., n. ep.
(Flam 5, 5, M
Shell small, inflated, subquadrata in outline; beak* high, near the anterior end,
excavate in front, strongly incurved, approximate; anterior end short, rounded,
curving to tbe rounded base; posterior end more produced, gaping; surface marked
only by concentric ridges which become weakened on the after part of the shell;
shell thin.
The holotype (Calif. Acad. Sci. type Coll.) and many other examples of the
species wore collected by N. E. A, Hinds near the Clements ranch on Redding Creek,
eastern Trinity County, Tho holotype has the following measurements: length,
41 mm.; height, 33 mm.; thickness of both valves, 27 HUD, The species somewhat
resembles Pholcdomya ru&telli, but it ia smaller, has more prominent beaks, and a
more produced posterior part. All the examples obtained were from the same
point, where they were associated with Pholadomya Clementina, and Phyllocerat cf.
in'niicnte nov., and they were found in strata near the horizon of the holotyp« of
Crioceroi latum Gabb. This horizon is believed to be in tbe upper part of the Paskenta
group,
Pkoladcmya cUmtnlina Anderson, n. ap.
(Phi* 3, fifum 3)
Shell small, little inflated, oval in outline; umbones high, eubcontral, angulated;
beaks incurved, approximate, excavated behind; posterior doraal margin rounded,
curving regularly to the narrowly rounded posterior end; anterior end eloping
rapidly to tbe basal border} surface Hiaooth, or having only faint concentric lines of
growth. The moBt characteristic, feature of the shell is the umbonal angle, extending
from the umbones to the angular anterio-basal border.
The holotype (Calif, Acad. Sci type Coll) was found by N. £. A. Hinds near the
Clements ranch on Redding Creek, eastern Trinity County, associated with the
preceding species. It has the following measurements: length, 37 mm.; height, 28
mm.; thickness of both valves, 18 mm,
The horizon la that of the preceding species, which ia believed to be in the upper