LOWER CRETACEOUS DEPOSITS CALIFORNIA AND OREGON
LOWER CRETACEOUS DEPOSITS CALIFORNIA AND OREGON
LOWER CRETACEOUS DEPOSITS CALIFORNIA AND OREGON
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description of species 221<br />
south at Locality 90S (Calif. Inst. Tech.), and half a mile east of the Jordan house.<br />
The stratigraphic position of tbe species is thought to be upper Aptian (Gargasiaa).<br />
Hemibacvlite$ nauplius Anderson, n. sp.<br />
(Plats M. tpja 3, 3a)<br />
Shell smaltj section elliptical, narrowing slightly toward the ventral border,<br />
costate, with low rounded, and nearly straight costae, inclining forward and crossing<br />
the ventral zone without interruption; ribs non-tubcrculate; dorsal zone nearly<br />
smooth, showing only depressed costae; septa as shown in the figure. The holotype<br />
(Calif. Acad. Sci. type Coll.) was found at Locality 1347 (Calif. Acad. Sci.) near<br />
Mitchell Creek, in the Mitchell zone, 5 miles south of Ono, Shasta County. It has<br />
the following dimensions; length, 100 mm,; greatest width, 30 mm,; greatest thickness,<br />
22 mm.; shell tapering gradually and showing only a slight tendency to curve.<br />
At its larger end there is a slight swelling and possibly the beginning of a more definite<br />
curve, Whether this shell possessed a retroversal body-chamber is not known.<br />
Thie species appears to belong to the group of uncoiled ammonoids represen ted by<br />
"Toxoceraa" obliquotum d'Orbigny, the genotype of Hyatt's genus. It was found<br />
at the top of the Mitchell zone, in a bed containing jSAailicn'cceras ponienfe nov.,<br />
Jnoceramus ovaloidea, and other apecies thought to represent an upper Qarremian<br />
horizon. It is the ol dest form of the genus found in the Cottonwood district. Only a<br />
single example of the specics was found.<br />
Hemibaeulites cyclopius Anderson, n. sp.<br />
(Plata 5$, figure 3; plate 60, figoraa 3,3a)<br />
Shell large, nearly straight, tapering gradually; acction broadly ovate, narrowing<br />
in outline section toward tbe ventral border, broadest near the opposite border, a<br />
little flattened on the dorsal zone, narrowly rounded on the ventral zone; sides<br />
moderately costate, with oblique, rounded, unequal riba, 2 to 4 mm. in width, arranged<br />
in groups of five or six, the central one stronger than the others; costal groups<br />
separated by slight depressions; septa shown in the figure. Tbe holotype (Calif.<br />
Acad. Sci, typo Coll.) has the following dimensions: total length (incomplete),<br />
388.8 mm. (15.3 inches); maximum diameter, 75 nun.; greatest diameter at smaller<br />
end, 38 mm.; median diameter, 67 mm. This example was found on Alderson Creek,<br />
2 miles south of Ono, Shaata County, in a shale bed about 200 feet above the horizon<br />
of Tropaeum pcrcoxtalum (Gabb), and 80Q tq M0 feet above the Mitchell zone with<br />
Shaxticriacerae panienie nov. It was associated with Lyloeeraebaien (Traak), A trots tttkis<br />
imprests (Gabb), and Phy Hoc eras onoenee Stanton. Thia example a haws no<br />
early coil nor any recurved body-chamber, although it exhibits some evidence of<br />
having possessed the latter, having a slight expansion in the ventro-don&l diameter<br />
at its bucal end. Thia is the longest example of this genua that haa boon found,<br />
although not the largest in diameter, being exceeded in this respect by ff. mfra&ffis<br />
nov. Only a single specimen of this species has been found.<br />
Hemibaeulites neleus Andcraon, n. sp.<br />
(Plate S», Octroi 3.2i, 3)<br />
Shell of medium size,, tapering very gradually, only slightly curved, section of<br />
shaft broadly elliptical, surface costate, with low, rounded, slightly curving ribs<br />
which cross the ventral zone without interruption, becoming faint in the dorsal zone;<br />
septa not well preserved. The holotype (Calif- Aead. Sci. type Coll.) consists of ft<br />
fragment of the shaft which ia costate throughout. It measures SI mm. in length;<br />
greatest diameter, 33 mm.; greatest transverse diameter, 30 mm. It was found at