io8 DISCOVERY REPORTS 



are very thin, never more than 4 mm. in height and show a narrow umbilical cleft, while those from 

 South Georgia are more solid, from 6 to 8 mm. in height, and have a spreading parietal callus without 

 a definite umbilical cleft. A range of topotypes will be required before anything further can be done. 



Laevilitorina claviformis Preston 



Laevilitorina claviformis Preston, 1916, p. 270, pi. 13, fig. 3. 



Type locality. Deception Harbour, South Shetlands, on rocks at low water. 



St. 179. Melchior I., Schollaert Channel, Palmer Archipelago, in creek to south of south-west anchorage, 

 10 Mar. 1927, 4-10 m. 



Subgenus Corneolitorina n.subg. 

 Type : Laevilitorina coriacea Melvill & Standen 

 (See above for diagnosis) 

 Laevilitorina (Corneolitorina) coriacea Melvill & Standen 



Littorina {Laevilitorina) coriacea Melvill & Standen, 1907, p. 130, pi. , fig. 2. 

 Type locality. Scotia Bay, South Orkneys, 5-10 fathoms. 

 St. 166. South-east point of Paul Harbour, Signy L, South Orkneys, 19 Feb. 1927, shore coll. 



Dentition. Fig. I, 27, p. 191 (St. 166). 



Pelseneer's Laevilitorina elongata (1903, pi. 5, fig. 58) from Two Hummocks Islands appears to be 

 closely allied. 



Genus Laevilacunaria n.g. 



Type : Pellilitorina bransfieldensis Preston 



(See above for diagnosis) 



Laevilacunaria bransfieldensis (Preston) 



Pellilitorina bransfieldensis Preston, 191 6, p. 271, pi. 13, fig. 5. 



Type locality. From stomachs of fish taken in Bransfield Straits, off Deception I., South Shetlands. 



St. i486. Harmony Cove, Nelson I., South Shetlands, 3 Jan. 1935, shore coll. 



Wilhelmina Bay, Danco Land, South Shetlands, 64 30' S, 62 W, 1-8 fathoms (A. G. Bennett). 



Preston failed to recognize in the above species a very close relative of the South Georgian species 

 described by Martens (1885, p. 92) as Lacuna antarctica. This species was admirably figured by Martens 

 & Pfeffer (1886, pi. 2, fig. i«-/and pi. 3, fig. 13), and on external characters there seems to be no 

 obvious differences between figures of the South Georgian shell and actual paratypes of Preston's 

 species. The radula of Preston's species, however, shows sufficient differences from that figured by 

 Martens and Pfeffer for the South Georgian antarctica, to warrant recognition of both names for the 

 present. 



Dentition. Fig. I, 29, p. 191. The radula in these shells is remarkable in having very broad chisel-shaped 

 cusps on both the central and lateral teeth. In detail the central tooth of bransfieldensis differs from that 

 of antarctica in being widest at the top, not medially, and in the cusp occupying most of the width of 

 that tooth, not half the width as shown in Martens and Pfeffer's figure. In bransfieldensis both laterals 

 have broad cusps with a small denticle on each side. In antarctica, however, the second lateral is shown 

 with a reduced, chisel-shaped main cusp and two strong, pointed cusps on the inner side. These 

 differences would seem greater than one can ascribe to either normal range of variation or to vagaries 

 in interpretation. 



A radula very similar to that of bransfieldensis is figured by Thiele (1929, p. 123) for Carinolacuna 

 carinifera A. Adams from Borneo. 



