Neithea grandicosta Gabb, 1869
GABB, W. M. 1866-1869. Paleontology of California. Vol II. Cretaceous and Tertiary fossils. Geological Survey of California, 299 p., pls. 1-36. [p. 200, pl. 33, figs. 99, 99a]
1869 Neithea grandicosta Gabb, 1869
W. M. Gabb, 1866-1869, plate 33.
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«SHELL minute, very inequivalve, equilateral, elongated; lower valve, sides tapering a little concavely; general contour of the base semicircular, with six prominent angles and concave interspaces. Surface marked by six very large, round, equidistant ribs, the interspaces carrying a small rib, flanked on each side by one still smaller; in some cases the sides of the large ribs are faintly striate; crossing these ribs are minute, very regular lines of growth; ears very unequal, the right ear long and deeply emarginate.
Length from beak to base, .5 inch.
Hare in the Shasta Group, Cottonwood Creek, Shasta County. This is one of the smallest, if not absolutely the smallest species yet described in the genus. It has some resemblance to N. duplicicosta, Roem. sp., of Texas, which has three intermediate ribs; but in that shell the large rib is very compound. It is most nearly allied to the French Neocomien species, N. atava, d'Orb. sp., but the ears are of a different shape; in that shell the right ear of the lower valve is much smaller, the interspaces are more concave, and the large ribs, instead of being simple, are made up of three smaller ribs.» WILLIAM MORE GABB, 1869
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«This species seems to be very rare in the Shasta series, and only the holotype has been known. Its horizon was not given by Gabb, and its exact locality has been conjectural. Recently a single valve clearly identifiable with the species has been found in the Barr zone of the Horsetown group, near the small school on Mitchell Creek, 5 miles south of Ono, Shasta County. Its length is 13 mm.; height, nearly the same. It was found associated with Acroteuthis aboriginalis, nov., Terebratella averilli, nov., and Parahoplitoides sp. Its occurrence in the thin conglomerate of this zone fixes its horizon here as in the lower Aptian beds of the Horsetown group.»
ANDERSON, F. M. 1938. Lower Cretaceous deposits in California and Oregon. Geological Society of America, Special Papers, 16: 1-331, pls. 1-84. [p. 110]
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«The specimen figured is the best of two now iu the Academy's collection and is taken for the lectotype. It seems reasonably certain that the original figure is a synthetograph of these specimens, for the species was cited as "rare" and was probably known ouly from these two specimens. The left side of the lectotype is slightly telescoped. The six prominent radiating ribs extend to the ventral margin which is therefore sinuous. The central interspace, at least, has three minor radials, of which the central one is the widest. Fine concentric ribs cross the radial sculpture and are sinuous, evidently following the growth lines. The right ear or wing is not complete, but it is the anterior one, the specimen being a right valve. Length, (incomplete) 9 mm.; height, 12.4 mm.; thickness, ca. 5 mm.; no. 4435.
Horizon, Cretaceous, "Shasta Group;" locality, Cottonwood Creek, Shasta Co. The matrix is a rather soft, dark gray, shaly sandstone. The three intermediate ribs on the central interspace suggest N. quadricostata (d'Orbigny, Pal. Fr. Crét. v. 3, 1843, p. 644, pl. 447, fig. 1-7) which is said to occur in the Cénomanien and Sénonien (Gillet, Bul. Soc. Géol., Fr. (4), v. 24, 1924, p. 117).» STEWART, R. B. 1930. Gabb’s California Cretaceous and Tertiary type lamellibranchs. Academy of Natural Sciences of Philadelphia, Special Publication, 3: 1-314, pls. 1-17 [p. 116]
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Neithea (Neitheops) grandicosta Gabb; R. B. Stewart, 1930, Gabb’s California Cretaceous and Tertiary type lamellibranchs, plate 1, figure 5.
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