12 
S. S. BUCKMAN, 
(Schwed. Südpolar-Exp. 
Hemithyris plicigera, Jhering, sp. 
Plate I, fig. lo. 
1897. Rhyjichonclla plicigera, JHERING, Moll. terc. 270, fig. 7 (teste Jhering 1903).' 
1901. ') î Ortmann, Princ. Exp. 70, PI. XII, 3. 
1903. 2> » Jhering, Brach, tert. 334. 
Remarks: One ventral valve showing plicæ towards the anterior margin, and 
a sinus with 3 small folds, looks as if it might be the young stage of R. plicigera. 
It has some resemblance to R. phcatodentata as figured by Davidson (Tert. Brach., 
XX, 2 c), but is flatter with less fold. 
Locality: Cockburn Island (13), off Graham Land, Antarctica. 
Formation: Glauconitic Bank. 
Material: One ventral valve. 
Other localities: R. plicigera is, according to J1IERING, found in the Lower, 
Middle and Upper Patagonian formation, Patagonia. 
Hemithyris australis, sp. nov. 
Plate I, fig. II. 
Description: Subpentagonal; dorsal valve slightly gibbons; ventral valve rather 
flat, with an anterior linguiform sulcus; both valves smooth except for some lines of 
growth. Beak short. 
Remarks: This species belongs to the Rynchonella bipartita series, but the sinus 
is narrower, more pronounced, and especially more developed in relation to size. 
The shell is not unlike R. bolcensis as figured by Davidson (Tert. Brach., XX, 4. 
1870), but the narrower and deeper sinus and a larger beak are sufficient distinctions. 
This is perhaps the shell that M‘COY (1867, p. 195) identified as R. liicida, 
Gould; but the less elongate figure and the more pronounced sinus prohibit the 
placing of the Antarctic fossil with the Recent species. 
Locality: Cockburn Island (13), off Graham Land, Antarctica. 
Formation: Glauconitic Bank. 
ALaterial: One imperfect specimen, somewhat crushed. 
Dates of similar species: R. bolcensis is Eocene, R. bipartita, Miocene and Plio- 
cene, and R. lucida, Recent. 
’ This work could not be seen. 
