TRANSACTIONS OF WAGNER 

 QOO 



TERTIARY FAUNA OF FLORIDA 



Other species of Spisula in the Miocene of the eastern United States 

 (chiefly Hemimactrd) are S. confragosa Conrad (= Mcsodcsma confragosa Conr., 

 Am. Journ. Sci., xxiii., p. 340, July, 1833; + Mactra fragosa Conr., Medial 

 Tert, p. 26, pi. 14, fig. 2, 1838; + Mactra incrassata Conr., Medial Tert., p. 

 24, pi. 13, fig. 2, 1838; + Mesodcsma confraga Conr., Proc. Acad. Nat. Sci., 

 1862, p. 574, 1863) from Maryland, Virginia, and North Carolina; S. (Afac- 

 iroiiicris) snbparilis Conr., 1841, from Wilmington, North Carolina; A", modi- 

 cella Conr., 1833, York River, Virginia; this last is not the same as RFactni 

 clathrodonta Lea, as supposed by Conrad; S. snbcuneata Conr., 1838, Mary- 

 land; and A", medialis Conr., 1863, which is probably from North Carolina, 

 though the provenance of the types is not precisely known. 



Section Hcnrimactra s. s. 

 Spisula (Hemimactra) densa m s. 



PLATE 27, FIGURE 22. 



Oligocene sands of Oak Grove, Santa Rosa County, Florida ; Burns. 

 Shell small, solid, smooth, or concentrically scuptured, with fine incre- 

 mental lines, and sometimes obscure radial striae near the margin ; subtri- 

 angular, subequilateral ; beaks small and low, hinge strong, the lamina; 

 sharply cross-striated; pallial sinus rounded, small, and very short; Ion. 14, 

 alt. 9.5, diam. 6 mm. 



This solid little species is stronger and larger than the majority of the 

 Eocene forms, and has the aspect of a Midinia. Its height is less than in the 

 allied Miocene types of about the same size, and its ends are more pointed. 



Genus MTJLINIA Gray. 



This form presents the last term in the submergence of the ligament, 

 and does not appear in the older Tertiary or even in the Oligocene, but in 

 the Miocene and subsequently it has attained a profuse development. The 

 student should bear in mind that much variation of outline exists within 

 specific limits in this genus and a new species should be founded in general 

 on a large number of specimens, otherwise the estimate of its characters is 

 sure to be defective. 



Mulinia congesta Conrad. 



j\lit<:ti-a congesta Conr., Am. Journ. Sci., xxiii., p. 340, 1833; Medial Tert., p. 27, pi. 

 xv., fig. 2, 1838. 



