273 Costa Rica Miocene— Olsson ioi 



last are in the form of broad, subobsolete, smooth bands without 

 the sculptured interspaces; there are about 15 spiral cords on 

 the last whorl in addition to those of the anterior canal; anterior 

 canal of moderate length, strongly twisted; columella with 4 

 plaits, heaviest above; aperture narrow. 



Ivcngth 74 (apex broken), diameter 23, last whorl 52, 

 spire 35 mm. 

 A single, large shell with rudely sculptured whorls was col- 

 lected from the coralline limestone near Port Linion. It agrees 

 closely with Reeve's figure of Mih^a Szvainsoni, except that the 

 spiral bands are larger and heavier. 



The Mitra Swainsoni is a West Coast shell belonging to the 

 Panamic province. It is distinguished b}' its large size, rudel}^ 

 sculptured whorls and dark colored epidermis. Dall has des- 

 cribed as the variety antillensis , specimens dredged off of Cape 

 Lookout, N. C, Colombia and Yucatan. 



Gatun Stage: Port Liinon. 



Mitra ionga Gabla Plate 6, figure 10 



Mitra tonga Gabb, 1873. Trans. Amer. Phil. Soc, vol. 15, p. 219. 

 Mitra tonga Brown and Pilsbry, 191 1, Proc. Acad. Nat. Sci. Phila.,vol. 



63, p. 346, pi. 24, fig. II. 

 Mitra tonga Maury, 1917, Bull. Amer. Pal., vol. 5, p. 238, pi. 11. figs. 



II, iia. 



A long, slender species, sculptured with strong, revolving 

 cords and fine, neatly engraved interspaces. We have collected 

 this Dominican species only in the Canal Zone. The figured spec- 

 imen has the following dimensions: 



Length 40, diameter 10.5, last whorl 26, spire 21 mm. 

 Gatun Stage: Gatztn, C. Z. 



Mitra dariensis Brown ond Pilsbry Plate 6, figure 25 



Mitra dariensis Brown and Pilsbry, 191 1, Proc. Acad. Nat. Sci. Phila., 

 vol. 60, p. 346, pi. 24, fig. II. 



