Pecten (Pecten) raymondi brionianus P. D. Trask, 1922
TRASK, P. D. 1922. The Briones Formation of middle California. University of California Publications, Bulletin of the Department of Geological Sciences, 13 (5): 133-174, pls. 1-8. [p. 148, pl. 1, figs. 2, 3]
«PECTEN (PECTEN) RAYMONDI BRIONIANUS, n. var.
Plate 1, figures 2 and 3
Type.—No. 12368; cotype—No. 12369, Univ. Calif. Mus. Pal.
Dimensions.—Type specimen U. C. no. 12368; alt., 37.3 mm.; width, 37.3 mm.; length of ears, 18.7 mm.; apical angle, 100°. Cotype, U. C. no. 12369; alt., 31.7 mm.; width, 32.7 mm.; apical angle, 100°. Occurrence.—San Pablo group. Type and cotype from U. C. loc. no. 3532. An analysis of over one hundred specimens of the forms of Pecten raymondi Clark found in the Briones and the San Pablo formations shows that there are two end varieties with a gradual gradation between. The San Pablo forms, as a general rule, possess a relatively more convex left valve, and higher and stronger ribs which are relatively close together. This is the typical P. raymondi described by Clark. [19] The forms found in the Briones have only slightly convex valves, and the ribs are relatively low and widely separated. The name P. raymondi brionianus is suggested for this variety.»
[19] Clark, B. L., Univ. Calif. Publ. Bull. Dept. Geol., vol. 8, p. 450, pl. 46, figs. 1 and 2, pl. 47, figs. 1 and 2, 1915.
PARKER DAVIES TRASK, 1922
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P. D. Trask, 1922, plate 1.
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