FREE INSTITUTE OF SCIENCE 



1047 



TERTIARY FAUNA OF FLORIDA ^' 



Shell small, thin, moderately inflated, ovate trigonal with prominent 

 pointed beaks; anterior end slightly longer, rounded, base arcuate, posterior 

 end attenuated with a small truncation at the tip ; surface polished, with rather 

 distant, very delicate, concentric, elevated lines ; interior with the pallial sinus 

 high, long, nearly reaching the anterior adductor scar, wholly confluent with 

 the pallial line below. Lon.- 10.5, alt. 6.25, diam. 3 mm. 



The single perfect specimen is a left valve and has only the cardinal teeth, 

 but the margins on each side of them project in a way unusual in this genus, 

 yet the associated fragments include hinges of both right and left valves of 

 undoubted Macoma which appear to be the same as the complete valve. It 

 may be a young shell of a species which reaches a considerably larger size. 



Macoma irma n. sp. 

 Plate 46, Figure 15. 



Oligocene of the silex beds at Ballast Point, Tampa Bay, Florida ; Dall. 



Shell ovate, moderately convex, short, with a marked posterior flexure, 

 nearly equilateral ; beaks not conspicuous, anterior end broad, rounded, pos- 

 terior atteuLiated, bluntly pointed, flexed to the right ; surface marked only 

 by rather rude incremental lines ; hinge-plate strong, teeth normal ; pallial 

 sinus obscure but apparently connecting the adductor scars, and wholly con- 

 fluent with the pallial line below. Lon. 28, alt. 20, diam. 10 mm. 



The specimens are rather poor pseudomorphs in silica, but evidently belong 

 to the genus Macoma and to a species distinct from any of the others listed 

 from this horizon. 



Macoma lenis Conrad. 

 Tellina lenis Conrad, Proc. Acad. Nat. Sci. Phila., i., p. 306, 1843 ; Fos. Medial Tert., 



p. 72, pi. 41, fig. Q, 1845. 

 Tellina lens Meek, S. I. Miocene Checklist, p. 10, 1864; err. typ. for lenis. 



Oligocene of the Oak Grove sands, at Oak Grove, Santa Rosa County, 

 Florida, Burns ; Miocene of Calvert Cliff, Maryland, Conrad ; of Jones Wharf 

 and Plum Point Landing, Maryland Geological Survey. 



The pallial sinus is rather short and wholly confluent below. The hinge- 

 teeth are very small and feeble, but the ligament long. A strong thickened 

 ray proceeds from the umbo radially behind the anterior adductor scar, and 

 the shell has the anterior end markedly shorter than the posterior, which is 

 not flexed and is lanceolately pointed, giving the shell the aspect of a Gas- 

 trana, but the surface sculpture is without radial striation. The presence of 



