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663 



TERTIARY FAUNA OF FLORIDA 



a few radial ribs near the middle of the valve, below which the sculpture 

 becomes obsolete; in chipolana the ventral areas are sculptured with distinct 

 oblique, concentric waves, with about equal interspaces; the upper ends of 

 these waves terminate abruptly where they meet the longitudinal riblets, so 

 that the sculpture of the ventral is strongly contrasted with that of the dorsal 

 areas. This form also appears to increase in width more rapidly than the 

 argcntca. On the whole, the two appear specifically distinct, but a complete 

 description must be deferred until better material enables the characters to be 

 fully elucidated. 



Atrina Harrisii n. s. 

 PLATE 29, FIGURE n. 



Types collected by G. D. Harris (in honor of whom the species is 

 named) from the Miocene at Jones's Wharf on the Patuxent River, Maryland ; 

 other specimens were found by him near Plum Point, Maryland, and a frag- 

 ment at Magnolia, Duplin County, North Carolina, by Burns. 



Shell rather thick (the fibrous layer lost in the specimens), ovately 

 rounded behind, moderately convex ; hinge-line straight, ventral margin 

 slightly incurved ; the surface of the pearly layer shows the dorsal region 

 with numerous fine longitudinal elevated lines, below which the shell is at 

 first nearly smooth, then the ventral region is sculptured with numerous 

 close-set concentric riblets. Length of portion preserved about 150, max. 

 width 60, diam. 32 mm. 



This species appears to have been not unlike A. serrata Sowerby, but 

 was a much heavier shell with a blunter anterior end. 



Atrina rigida Dilhvyn. 

 rinna tcnuis strhita nnincala Lister, Conch., t. 370, f. 310; Sloane, Hist. Jamaica, p. 



254. 



I'inini nobilis Chemn., Conch. Cab., vii., p. 224, ex ptirlc, pi. 88, fig. 775, non Linne. 

 /'/ii/iii /'< -/iiiiitii Iiorn, Test. Mus. Vinci., p. 132, non Linn6. 

 J'inna ri^i,tii (Solander MSS.) Uillwyn, Cat., p. 327, 1817; Reeve, Conch. Iron., I'iitihi, 



pi. v., i\. 7, 1858. 

 I'iniiii scniiiiiiihi Lam., An. s. Vert., vi., p. 131, 1819; not Reeve, Conch. Iron., I'inna, 



pi. ii., fitf. -. 1858 (= sfi-rata Shy.). 



rin 11,1 ,i//,r Shy., P. 7. S., 1835, p. 84; Reeve, Conch. Icon., vi., fitf. u. 

 suli-'ii-ii/is Reeve-, Conch. Icon., J'inini, xvii., li^. 32, 1858. 



ii' OH'i^iiyi Hanley, P. /. S., 1858, p. 227 ; Reeve, of>. fit., xxvi., fij, r . 49. ' 8 5 8 - 

 ouvtiiifiisis Hanley, P. /.. S., 1858, p. 225 ; Reeve, <>/>. <//., \\xiv., 1'^. 66, 1859. 



