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897 



TERTIARY FAUNA OF FLORIDA ^' 



arm of the right cardinal in h'ne with the ventral lamina, both very short. 

 Lon. 50, alt. 34, diam. 15 mm. 



This species is perhaps as near 5. delumbis as any other, but is smaller 

 and more compressed. The laminae are quite short and not striated. 



Spisula (Hemimactra) delumbis Conrad. 



Plate 27, Figure 26. 



Macfra delumbis Conr., Fos. Sli., p. 26, pi. 11, 1S32 ; Tert. Fos., p. 27, pi. 15, fig. i, 



183S ; Pi-oc. Acad. Nat. Sci. Phila. 1862, p. 572, 1863. 

 Mactra. virginiana Conr., Am. Journ. Conch., iii., pp. 188, 269, pi. 22, fig. 4, 1867. 



Chesapeake Miocene of the James River, Virginia, at Smithfield and 

 Suffolk ; of the York River, at Yorktown, Virginia, and in Maryland, at St. 

 Mary's City; Burns and Harris. 



This fine species was early described by Conrad, who, many years after, 

 obtaining specimens of S. marylandica, perpetrated one of his characteristic 

 blunders by re-describing the old species and leaving the new one still name- 

 less, his intention, of course, being to do just the reverse. 



Spisula (Hemimactra) marylandica n. s. 

 Plate 28, Figure 5. 



Chesapeake Miocene of Jones's Wharf, Patuxent River, Maryland, of 

 St. Mary's River, Maryland, Burns ; and of Walton County, Florida, L. C. 

 Johnson. 



Shell large, subovate, thin, inflated, with a nearly smooth surface, marked 

 chiefly by incremental and obsolete radiating lines ; beaks high, subcentral, 

 adjacent; anterior end excavated above, rounded in front, posterior sloping to 

 a bluntly pointed end behind ; anterior dorsal area rather smooth and deeply 

 impressed ; posterior area somewhat depressed, striated, flexuous, with three 

 obscure, elevated lines, extending from the umbo to the margin outside of the 

 area ; base arcuate ; pallial sinus rather narrow, extending nearly to the middle 

 of the shell, bluntly pointed in front; hinge strong, with a large oblique chon- 

 drophore, very short, smooth lateral laminas, and the anterior arm of the right 

 cardinal tooth coalescent with the ventral lamina. Lon. 90, alt. ^j, diam. 

 40 mm. 



This fine species is at once differentiated from 5". dchivibis by its more 

 equilateral and inflated shell, and by having instead of only one three elevated 

 lines radiating backward from the beak. 



