LOWER CRETACEOUS DEPOSITS CALIFORNIA AND OREGON

de8cbjpti0m OW species W5
to bave near relationships with those of earlier date. Lytoceraa bolesi (Trask) appears
for the first time in Bedoulian time, but continues for only a short span and is
replaced by others in Gargoaian and later time. Still later, in Albian time, another
assemblage entered the embayment, but there seems to have been little, if any, relations
between its constituents and those of the earlier "waves." Thus in the course
of the Shasta period three or more groups of lytoceratids, having no closa relationships,
appeared in succession. It would be in harmony with the physical history of
the VVest Coast during this period if these successive "waves" were regarded S8
being so many distinct immigrations, or invasions, coming from distant regions in
which they had been cradled. Some of these stocks seem to have allies in southwest
Asia (Spiti, Cutch, etc.). The lytoceratida of the Shasta series can be separated
into aa many as six subgancrtc groups, followed by others in the early part of the
Chico series (Cenomanian).
The order of their occurrence appears to be about as follows:
(1) Valanginian time.—
Lylocerat (Sa(«nwceroa) eaturnaltf, n, eubgen., n. ap.
L. traski n. ap.
L. rel. (roehi n, ap.
L. autaeum n. sp,, rel, L* eaturnale, nov.
(2) Aptian time.—
ffabWoceroa anjulalum Anderson; G. utniuntum n. sp.
Lyiocerat (Arponaulieeras) aT$on&iitartim (Andereon)
L, &«feri (Traek)
(3) Albian time.—
Lytacertu (Gaudrycerat) taeya (Forbes)
L. (7 GaudryeerOM} nejfiamanum. n. sp.
L. (KotsmaUUa) tchiineyi (Gabb)
L. iKotimaUUa) aurarium n. ap,
L. (? Kotsmaltlla) gaineai n. ap.
(4) Cenomanian time.—
Forms of Gaudrycerat and Tetrancmitee, only, are known from the Chico
scries, following the close of the Shasta series,
Lytocerat (Solwrftoetrtu) taiurnai-e Anderson, n. sp.; n. subgenus
(Plata a Stun I)
In Ma account of Lytaceras baieti (Trask), Gabb (1364, p. 07) refers to an incomplete
specimen 15 inches in diameter, found in the Bald Bills, Shasta County; he
gives also other measurements. This specimen is in the Museum of Faleeiftalogy,
University of California, and has been examined with rouch caro. Very clearly it
does not belong to the species to which Gabb referred it, nor is it nearly related to it.
This example constitutes the holotype of the present species, and the genotype of the
group to which it belongs. It haa the following dimensions; greatest diameter, 16.5
inches (419 mm.); width of umbilicus, 7 inches (178 mm.); height of whorl, 5.5 inches
(138 mm.); width of whorl, 6 inches (152.6 mm.); umbilical ratio, 0.424:1.
It was at one time thought that this specimen might represent Lytoaerm argofiaularum
Anderson, but later coliectiona and comparison with examples of the latter
proves that this was an error; the two forms are not nearly related.
Stanton (1895, pi. 13) has figured a lytoccratid from the Wilcox ranch, Tehama
County that seems to conform to the characters cf the holotype, insofar aa can be
determined. Stanton notes the crenulations on the costal ridges and compares it to
Amm. cTtnocotlolua Whiteaves, later referred by its author to L, bflWit (Trnsk).
Stanton's example came from the Paakenta group an the Wilcox ranch, from which