Pecten (Plagioctenium) callidus Hertlein, 1925
HERTLEIN, L. G. 1925. Pectens from the Tertiary of Lower California. Proceedings of the California Academy of Sciences [4th Series], 14 (1): 1-35, pls. 1-6. [p. 22, pl. 5, fig. 1, 3, 5, 6]
16. Pecten (Plagioctenium) callidus Hertlein, new species
Plate 5, figures 1, 3, 5 and 6 Shell of medium size, the valves moderately arched. Right valve ornamented by about 21 or 22 rather high, flat-topped, radiating ribs separated by narrower interspaces, tops of ribs smooth, but sides and interspaces sculptured by fine, sharp lamellae; anterior and posterior margins sculptured by concentric lines of growth only; ventral margin rounded; ears unequal, the anterior with a large byssal notch and ornamented by about five or six radiating riblets crossed by concentric lines of growth ; the posterior sculptured by several radiating riblets. Left valve more convex than right and somewhat one-sided in appearance, with sculpture quite similar to that of right valve except that the interspaces are slightly wider; anterior ear carrying a small, rounded notch and ornamentation consisting of small, radiating riblets and concentric lines of growth; posterior ear sculptured much as the anterior. Altitude 55 mm.; longitude 55 mm.; diameter 19 mm.; apical angle of valves approximately 105°.
Type: No. 53 (L.S.J.U. type collection), from Loc. 116 (L.S.J.U.), Cedros Island, Lower California; Paratypes: No. 54 (L.S.J.U. collection), H. Hemphill collector; Salada, Pliocene. This species was found also at Loc. 48 (L.S.J.U.), from mouth of big Arroyo northwest of Elephant Mesa, Scammon Lagoon Quadrangle, Lower California; B. F. Hake collector; Salada Pliocene. In the Fernando Lower Pliocene of southern California, at several localities, this species also appears to be quite abundant. Pecten callidus differs from P. subdolus Hertlein in having higher, narrower, smooth rather than striate, flat-topped ribs, the interspaces crossed by very fine lamellae which are largely lacking in P. subdolus. It differs from P. cerrosensis Gabb, in its larger byssal notch, radially sculptured ears, more numerous ribs, and usually smaller size. Possibly P. callidus was the square ribbed species from the Fernando formation of southern California which Arnold referred to P. cerrosensis». LEO GEORGE HERTLEIN, 1925
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L. G. Hertlein, 1925, plate 5.
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