Lepidopecten scissuratus Dall, 1898
DALL, W. H. 1898. Contributions to the Tertiary fauna of Florida. Silex Beds of Tampa and the Pliocene Beds of the Caloosahatchie River. Part IV. I. Prionodesmacea: Nucula to Julia. 2. Teleodesmacea: Teredo to Ervilia. Transactions of the Wagner Free Institute of Science of Philadelphia, 3 (4): viii, 571-947 p., pls. 23-35 (pls. 36 and 37 in part 5, 1890) [p. 715, pl. 34, fig. 4]
1898 Pecten (Aequipecten) scissuratus Dall, 1898
1911 Pecten effossus Brown & Pilsbry, 1911
1911 Pecten pinnulatus Toula, 1911
1911 Pecten effossus Brown & Pilsbry, 1911
1911 Pecten pinnulatus Toula, 1911
W. H. Dall, 1898, plate 34.
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«Oligocene of Ponton, St. Domingo, and ten and a half kilometres west of Colon, Isthmus of Darien; Hill.
Shell moderately compressed, with sixteen well-marked ribs; valves nearly equilateral, the right one less flat than the other; disk suborbicular, with small subequal ears; left valve with the ribs smooth and rounded on top, separated by subequal, slightly channelled, smooth interspaces; the ribs on each side just below the top are incised by a sharp, narrow groove, in which are closely set small imbricated scales, which seem easily detached, so that in the worn specimens the sulcus alone remains, ending in a narrow, sharp slit at the distal end of the rib; the ears are flat, with sparse radial threads; in the right valve the ribs are squarish and smooth, the sulci are absent, and the surface sculpture confined to faint incremental lines; the ears have a few imbricate radii, and the notch is shallow; the submargins are narrow and young shells have a polished surface; the internal surface is channelled in harmony with the external ribbing; the auricular and cardinal crura moderately developed. Alt. 31, lat. 30, diam. about 6 mm. In young shells the sulci on the ribs are not conspicuous, and in perfect ones the scales must more or less completely hide the grooves.» WILLIAM HEALEY DALL, 1898
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«Of medium size, right valve more convex than left wherever they are associated, but convexity of both variable, ranging from 2.7 to 6.3 mm for right and 2.4 to 5.2 mm for left. Ribs and concentric lamellae appearing at height of 0.5 mm on wellpreserved valves. Right valve sculptured with 16 to 18 ribs (generally 17), slightly narrower to slightly wider than interribs. Concentric lamellae weak or absent on ribs, weak or strong in interribs. Left valve sculptured with 14 to 18 ribs (generally 17 or 18). At height of about 10 mm, a very thin radial lamella appearing on both edges of ribs. Space between rib and lamella filled with crowded low vaulted scales, generally broken down to base, or effaced along parts of some ribs, leaving narrow groove along rib flanks. Concentric lamellae generally conspicuous in interribs. Radial sculpture equal on anterior and posterior auricles; that of right valve moderately strong, that of left valve weak or moderately strong. Byssal notch, byssal fasciole, and ctenolium not discernible, even on smallest right valve (height 9 mm). One or two pairs of cardinal crura and a pair of auricular tubercles generally recognizable.
Length 30.7 mm, height 31 mm, convexity 3.7 mm (type). Length 30 mm, height 29.6 mm, convexity 6 mm (larger figured right valve). Length (incomplte) 25.5 mm (estimated restored length 38 rom), height 38.6 mm, convexity (both valves) 8.2 mm (largest specimen). Type (left valve): USNM 113670. Type locality: Recorded as Ponton, Dominican Republic, but that record is rejected in favor of Mount Hope, Canal Zone, upper part of Gatun formation, as was done for Phos metuloides (P 306–C, p. 266) and Terebra spirifera (P 306–D, p. 409). Dall well described this species but assigned an erroneous locality to the type. There is no reasonable doubt that it was collected at Mount Hope, presumably by Rowell. The species is unknown in the Dominican Republic. Brown and Pilsbry's Pecten scissuratus from that country, which occurs in the Gurabo formation, is not closely related. Dall identified his species in Hill's collection that is thought to have been made at Mount Hope (locality 173a); in fact, the only right valves available to Dall are in Hill's collection. Lepidopecten scissuratus is found in the middle and upper parts of the Gatun formation: a little more than 100 specimens, including 34 topotypes. The largest specimen –the only one articulated– and the smallest unequivocally identified (height 7.5 mm) are topotypes. The sculpture of the left valve is shown to better advantage on the immature specimen illustrated on plate 106, figure 5, than on the type. The type material of Pecten effosus consists of two immature left valves, the larger incomplete. Occurrence: Middle and upper parts of Gatun formation (middle Miocene). Middle part, eastern area, localities 142, 147b, 147h, 151, 153a, 155, 155a, 155b, 159; western area, localities 160d, 161a, 169 (immature, identification doubtful). Upper part, eastern area, localities 171, 172, 173a, 175, 176, 176a, 177, 177a, 177b, 177c, 177d, 178. Deposits of Miocene age, Falcon, Venezuela (Hodson, Hodson, and Harris' record).» WOODRING, W. P. 1982. Geology and paleontology of Canal Zone and adjoining parts of Panama. United States Geological Survey Professional Paper, 306-F: 1-759, pls. 83-124. [p. 593, 594]
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Lepidopecten scissuratus (Dall); W. P. Woodring, 1982, Geology and paleontology of Canal Zone and adjoining parts of Panama, plate 106, figures 1, 3-5.
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