355 



Costa Rica Miocene — Olsson 



Shell small, thin, convex, subrhomboidal in form; umbos 

 wide and full; with the beaks at the anterior 1-3 of the shell; a 

 rounded posterior umbonal slope; the anterior extremity is brok- 

 en in the type specimen but from the earlier growth lines is 

 simply rounded in form; the posterior side is obliquely truncate 

 and meets the dorsal margin in a well-marked angle; the exteri- 

 or is sculptured like that of Area barbata, with the riblets group- 

 ed in wide, regular bands which are defined by slightly deeper 

 interspaces; the radial riblets are crossed and crudely granulat- 

 ed by concentric threads; the sculpture on the posterior submar- 

 gins is much heavier and predominantly radial that of the an- 

 terior submargin is but slightly heavier than on the middle of 

 the shell disk; interior of shell cavity deep, with a straight hinge- 

 margin, the teeth arranged as in barbata-, cardinal area rather 

 high, longitudinally striated posterior of the beaks, plain in 

 front. 



Length 24? height 11.50, semidiameter 5.50 mm. 



This species is closely related to the recent Area barbata 

 lyinne. It differs from barbata in its proportional shorter shell, 

 greater convexity, less anterior beak and higher cardinal area. 

 It is equivalent to the Dominican shell figured by Dr. Maury as 

 Barbatia cf . Bonaczyi Gabb. Gabb in his remarks following his 

 his description of Bonaezyi, compares his shell with barbata^ and 

 states that in Bonaczyi, the beaks are more anterior and the pos- 

 terior end more produced and sloping. This is the reverse of 

 the conditions as seen in the present shell. Dall on the other 

 hand, considers Gabb' s shell as synonymous with^rr<2 ufnbo?ita 

 Lamarck. 



Gatun Stage: Port Limon. 



Section CALLOARCA Gray 

 Area cf. Candida Gmelin Plate 22. figures 5, 6 



Area Candida GmcHn, 1792, Syst. Nat., p. 3311. 



Barbatia {Calloarca) Candida Dall, 1898, Trans. Wagner Free Inst., 

 Sci., vol. 3, pt. 4, p. 626. 



