Pecten wahtubbeanus var ? willcoxii 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, 1900). [p. 737, pl. 29, fig. 4]
«Pecten (wahtubbeanus var. ?) Willcoxii n. s.
PLATE 29, FIGURE 4. Eocene of Clarke County, Mississippi, and of the Wahtubbee hills (Claibornian); Johnson and Burns.
Shell small, broad, flattish, thin; left valve with about sixteen narrow, rounded, elevated ribs, with somewhat sparse, regularly spaced prickles on their tops; between the ribs are similar, but lower and smaller, non-dichotomous radial threads; submargins very narrow, nearly plain, with faint Camptonectes striation; ears small, subequal, except the byssal ear, which is longer, narrow, with a deep sinus and conspicuous fascicle, and about six scabrous radii, the right posterior ear with concentric striae and only faint traces of a few radii; the cars on the left valve similar, with five or six strong scabrous threads; internal basal margin of left valve with short flutings in harmony with the radial sculpture; the disk not grooved; in the right valve the internal channels are more pronounced; the right hinge-line has a single crural ridge parallel with the margin on each side of the pit. Alt. 23, lat. 24 mm. This form is closely related to P. wahtubbeanus, from which it differs by the isolated character of the prickles on the ribs, which are replaced in wahtubbeanus by more or less continuous concentric lamellation, while the ribs of the right valve of the latter are more or less split up, but in P. Willcoxii present the appearance of a fascicle of separate threads. In worn specimens of wahtubbeanus the ribs appear rounded and plain after the removal of the scales; in Willcoxii the division into threads is distinct. Nevertheless it is possible that a larger series may show the two forms to be merely the extremes of a single species. From P. membranosus the present form is easily distinguished by wider hinge-line, larger ears, thinner shell, and by its radial threads fasciculated rather than subequally level. It is named in honor of Mr. Joseph Willcox, to whom our Tertiary Paleontology is so much indebted.» WILLIAM HEALEY DALL, 1898
|
W. H. Dall, 1898, plate 29.
|