407 



Costa Rica Miocene — Olsson 



235 



Callista maculafa Gsibh, 18S1, Journ. Acad. Nat. Sci. Phila,, 2nd series, 

 vol. 8, p. 372. 



Macrocallista [Chionella) macnlata Dall, 1903, Trans. Wagner Free 

 Inst. Sci., vol. 3, pt. 6, p. 1256. 



Macrocallista niaculata Brown and Pilsbry, 191 1, Proc. Acad. Nat. Sci. 

 Plila., vol. 63, p. 370. 



The Macrocallista macnlata is a common and widely dis- 

 tributed fossil in the Costa Rican Miocene and is readily recog- 

 nized by its depressed, porcellaneous and highl}^ polished shell. 

 In the usual sand}^ phases of the Gatun, the species is quite typi- 

 cal, but becomes high and broad in the coralline or transitional 

 phase. 



A variety cuneata has been proposed by Gabb to include 

 shells in which this posterior-dorsal slope is straight and not 

 humped as usual. We have seen no examples of this type. 



The Macrocallista inaculata is a common recent species of 

 the West Indies, appearing for the first time, in the lower Mio- 

 cene beds of the Chipola River, Florida. 



Gatun Stage: Headwaters of Middle creek. 

 Rio Blanco. 



Genus CALLOCARDBA, A. Adams 



Subgenus AGRIOPOMA. Dall 

 Caliocardia gatunensis Dall • Plate 32, figure i 



Callocardia [Agriopoma) gatunensis Dall, 1903, Trans. Wagner Free 



Inst. Sci., vol. 3, pt. 6, p. 1260, pi. 54, fig.i. 

 Callocardia [Agriopoma) gatunensis Brown and Pilsbry, 191 1, Proc. 



Acad. Nat. Sci, Phila., vol. 63, p. 370. 



A convex, cordate shell very abundant in the Gatun beds 

 of the Canal Zone, especially in the quarries at Mt. Hope. It 

 is a rare species in Costa Rica, but generally larger, more trian- 

 gular in outline and somewhat coarsely sculptured. These shells 

 are nearest to Ball's variety multifilosa. 



