LOWER CRETACEOUS DEPOSITS CALIFORNIA AND OREGON

description of species 181
to that shown by d'Orbigny for Ammonite* laiidoraaitu, to which this species seems
closely related. According to Kilian and Reboul (1901-1908, p. 25), thiB form should
be referred to Koeamaiiceraa (group of Madranlee bhacani (Stoliczka)), but the
basis for this view is not clear and needs confirmation. They have included under
Koeem/Uicerae various ammonite forms from widely separated horizons in California
and British Columbian sections, ranging from. Jurassic to Senonian, although most
of the species described as such from Seymour Island and Snow Hill seem to be
Senonian in age. Dcemoeeras voyi somewhat resembles D. dawstmi Whiteaves, with
which Yabe has compared it, although regarding them as distinct. D. wyi occurs
in the Argonaut zone (middle Horsetown) where it ts associated with Lyloceraa bo(Mi
(Trask) and Melchioritee ehaatensia nov. in a middle Aptian horizon of the Cottonwood
district, Shasta County. The holotype of D, voyi Anderson is in the Museum
of Paleontology, University of California, and was found by the writer on the North
rork of Cottonwood Creek, near Ono, Shaata County. Other examples have since
been found in or near the Argonaut zone. It has tbe following dimensions: greatest
diameter, 53.3 mm.; width of umbilicus, 8.4 mm.; height of whorl, 31.5 mm,; thickness
of whorl, 28 mm.; umbilical ratio, 0.157:1. Specimens from the southeastern
part of Graham Island, 2 miles north of the Indian village of Skidegate, which are
indistinguishable from the California types, are in the collections of the California
Academy of Sciences. They occur there associated with Lyloceraa argona ularum
Anderson, and with indigenalie nov., and other Aptian species. An example
of Deam&eetaa otryi from thia place, with an example of AuceUa adhering to it, is
figured on Plate 40 (figs. 6, 7,8, and 8a). D. voyi was erroneously referred by Kilian
and Reboul (1000, p, 25) to the upper Gault of the California sedtion, although as
stated in tho original description its stratigraphical position is much lower. It is
the oldest species of Deamocerae («. a.) yet recorded from the Lower Cretaceous of the
West Coast,
Bcemoteras (Laiidoraella) merriami (Anderson)
(PUtott. flcuns 1,1)
Ammonite* Hoffmaimi GABS (in part), Paleont. Calif., vol. 2,1869, p. 131, pi. 20, figs.
8, Sa; Cottonwood Creek, Shaata County.
Pachydiscua merriomi ANDERSON, Calif. Acad. Sci., Pr., 3d aer., vol. 2, 1002, p. 103,
pi. 6, figs. 135-138; Hulen Creek, Shasta County, California.
The holotype of this spcciea ia in the Museum of Paleontology, University of
California, and ten or more examples of it from the locality of the type are in the
collections of the California Academy of Sciences, including the figured specimens.
The specimen figured by Gabb as the thicker form of Ammonilta hoffmanni is in
the collections of the Academy of Natural Sciences of Philadelphia and was loaned for
examination and comparison. It is a good example (siD. nterriami 1 and, according to
Gabb's notation, appears to have come from the Neptune zone on the North fork of
Cottonwood Creek. This example was made the genotype of Hyatt's proposed
genus "Pleitropachydiacut," which, if it has validity at all, should be regarded as a
subgenus of Desmoccraa Zittel and by priority Bhould replace "Latidorsella" Ch.
Jacob. The holotype of Deamocerae merriami (Anderson) has the following dimensions:
greatest diameter, 07 mm.; width of umbilicus, 17 mm.; height of whorl, 51
mm.; width of whorl, 47 mm.; umbilical ratio, 0.175:1. It ia septate throughout,
and is the inner whorl of a much larger example. Fragments have been found that
* By same miscbaBce, not dua toth* lutW, a page at tbe original ounuacript (KHK>, Intended tor & follow.
Im ap«elu,—Pedniiteu* JUn/wwi*,—wu Included ia tho diMbptkiii •! D. mmiumi, to which other error*
were addtd in comparing tbe spcciea with " PaelydUcu*" tveiatnrit (G*h1t), Dal Heck.