_ MOLLUSCA.—HEDLEY. 47 
indefinite furrows. Aperture entire, ovate, angled above, roundéd below, outer lip 
simple, slightly everted, inner lip separated by a narrow crack from the preceding whorl. 
Length, 2:7; breadth, 1mm. 
This species is called after Mr. James Cosmo Melvill, the senior author of a valuable 
report on the Antarctic Mollusca of the “Scotia”? Expedition, so often quoted in these 
pages. 
A dozen specimens were obtained, March 17th, 1912, at Garden Bay, Macquarie 
Island, by Mr. H. Hamilton, who notes that it was “ common under stones, above 
ordinary high-water level, but close to the sea”’. 
OVIRISSOA gen. nov. 
The southern shells usually included under Rissoa were recently discussed 
by Mr. T. Iredale,* who shows that this generic name is not applicable, and offers, 
instead, several new divisions and names. The polar species were not included in his 
scheme. So Ovirissoa, typified by Rissoa adarensis Smith, is proposed for a group 
from Antarctic waters of milk-white, glossy, imperforate, rather elongate small shells 
with about five convex whorls and an entire aperture. 
Other species of Ovirissoa are O. cazini Velain, from St. Paul’s Island ; O. columna 
Pelseneer, from Charcot Land; and O. georgiana Pfeffer, from South Georgia. 
OVIRISSOA ADARENSIS Smith. 
Rissoa adarensis Smith, Coll. “ Southern Cross,” 1902, p. 205, pl. xxiv., fig. 17; Id., 
Smith, Nat. Antarct. Exped., ii., 1907, p. 8, pl. il., fig. 2; Id., Melvill and 
Standen, Trans. Roy. Soc. Edinb., xlvi., 1907, p. 182; Id., “Scotia” Zool., v. 
1907, p. 102; Id., Lamy, 2nd Expéd. Antarct. Frang., u., 1911, Moll., p. 10; 
Id., Hedley, Brit. Antarct. Exped., ii., 1911, p.5; Jd., Smith, “Terra Nova” 
Exped., Zool., ii., 1915, p. 65. 
Six specimens were dredged, September 3rd, 1912, from 25 fathoms, in Common- 
wealth Bay. 
SUBONOBA BICKERTONI sp. nov. 
(Plate VII., fig. 76.) 
Shell elongate-ovate, imperforate. Colour, uniform light brown. Whorls five, 
wound rather obliquely with impressed sutures. Sculpture: very delicate wide-spaced 
spiral threads. Aperture oblique, elliptical, lip slightly everted, in contact with the 
body whorl for a short space only. Length, 2:7; breadth, 13mm. 
One specimen (type) dredged, December 14th, 1913, in 45-50 fathoms, in Common- 
wealth Bay. Fifty, September 3rd, 1912, from 25 fathoms, Commonwealth Bay. 
* Tredale.—Trans. N.Z. Inst., xlvii., 1915, p. 447. 
