LOWER CRETACEOUS DEPOSITS CALIFORNIA AND OREGON

description of species 167
diameter, 20 mm.; width of umbilicus, 5.5 mm.; height of whorl, 11 mm.; greatest
thickness, 6 mm.
This example was found associated with Acraleuthit mtuaTthyensi* nov., Acroieu-
(hit n. ap,, Aucella crassa, A. inflate, A. eratsicoUis, and a few other species, in the
h&aal conglomerate of the Shasta series (Paskenta group), marking a distinct unconformity
between this scries and the underlying Knoxville sandy shales.
Neoamtitet riddlensis Anderson, n. sp.
(PUts 30, fliurw 1,3, J, 4}
Shell of moderate size, discoidal, compressed, with small umbilicus; ventral zone
rather broad, flattened, angulated on its borders; sides mostly smooth below but
costate on the upper half, with about 38 to 42 rounded costae which carry at their
termini small elongated tuberculea; co&tae separated by concave interspaces, somewhat
broader than the ribs; costal lines flexed, curving strongly forward below the
periphery, crossing the ventral zone without interruption, and with a slight forward
bend; costal lines terminating at the umbilical border in umbilical bullae having a
slight backward Blant; suture lines not well exposed, but tripartite, and showing
hoplltid characters.
The young shell of this species, with a diameter leas than 30 mm., is nearly smooth,
having only costal lines and faint sub-peripheral coBtae, terminating in small elongated
tuberculea on the ventral border; tbe flattened ventral zone ia nearly smooth,
the umbilicus small with abrupt walls. In its young stages this shell has the form of
Neoccmiiea neocomien&ia d'Orbigny, although it has a smaller umbilical ratio. In
examples of a diameter of more than 60 mm., the umbilical bullae begin to appear,
from which the costal linea radiate in small groups.
The holotype and paratypes of this species are the property of the Oregon State
College and were obtained by E. L. Packard at Locality 253 (Oreg. State Coll.),
about a mile southeast of Riddle, Oregon, in beds that seam referable to the upper
part of the Paskenta group (Upper Valanginian) as known in California. The
holotype has tbe following dimensions: greatest diameter, 78 mm.; diameter of
umbilicus, 22 mm.; height of whorl, 38 mm.; thickness of whorl, 21 mm.; umbilical
ratio, 0.232:1. In form and seulpturet he species resembles Neocomite* monianu*
Uhlig (1903, p. 249, pi. 90) from the Valanginian part of the Spiti shales, to whieh
form it may be related,
Boehianxta Lory 1898
Bcckianittv pcukentaenvie Anderson, n. sp.