612 SYSTEMATIC PALEONTOLOGY 



ANOMIA ORNATA Gabb 

 Plate XXXV, Figs. 5, 6 



Anomia argentaria var. ornata Gabb, 1876, Proc. Acad. Nat. Sci., Phila., p. 



320. 

 "Anomia argentaria (Gabb) " Boyle, 1893, Bull. U. S. Geol. Survey, No. 



102, p. 44. 



Description. " Accompanying these is another form, represented by no 

 less than fifteen specimens agreeing well with one another. Unlike the 

 typical A. argentaria, they are ornamented by a uniform pattern, clearly 

 not the impression of a surface to which they were attached. In form and 

 size they do not differ from .4. argentaria, but the ornament is a series of 

 radiating ribs, one set large, flattened on top, and well defined; between 

 these are interpolated from one to three smaller ribs. In most cases this 

 alternation is well defined ; though in two or three the large ribs are nearer 

 in size to the small ones. On the typical argentaria this radiation is never 

 observed, even in a rudimentary manner, and on some of my specimens it 

 begins at the very apex ; but on several the first half inch in diameter, or 

 less, of the shell does not differ from argentaria, while after that the ribs 

 begin, first on thread-like lines, finally developing to full size. In conse- 

 quence of this I feel reluctant to separate the form as a distinct species, 

 believing that more material will merge the two. I therefore content 

 myself with proposing the name A. argentaria var. ornata." Gabb, 1876. 



Type Locality. Pataula Creek, Georgia. 



Ligament submarginal, lodged in a transverse pit directly beneath the 

 umbone of the left valve ; adductor and byssal scars grouped within an 

 ovate area coated with lime extending from the ligament pit more than 

 half-way to the ventral margin and occupying more than one-half the 

 width of the shell, major byssal scar near the center of the whitish area, 

 slightly ovate in outline; minor byssal scar and adductor ventral to the 

 major cicatrix, subequal in size, semi-elliptical, their straight faces proxi- 

 mate, the adductor the posterior of the two ; major and minor scars united 

 for a short distance along the dorsal face of the latter. 



Although most of the individuals which are certainly referable to 

 A. argentaria Conrad develop a faint radial lineation, none in the abund- 



