SYSTEMATIC 115 



Genus Acirsa Moerch, 1857 



Type (Cossmann, 191 2): Scalaria costulata Mighels 



Acirsa antarctica (Smith) 



Scala antarctica Smith, 1907, p. 8, pi. 1, figs. 10, 10b. 

 Epitonium antarcticum Smith, 191 5, p. 64. 



Type locality. Hole 12, 'Discovery' Winter Quarters, McMurdo Sound. 



St. 1660. Ross Sea, 74 46-4' S, 178 23-4' E, 27 Jan. 1936, 351 m. (two juveniles). 

 Recorded by Smith (191 5) from the Ross Sea, 158 fathoms. 



Acirsa annectens n.sp. PI. VII, fig. 23 



Shell moderately large, attenuated, of rapidly increasing convex whorls, dull white, solid, axially 

 costate but axials subobsolete on last two whorls. A prominent supra-sutural spiral fold forms a heavy 

 carina on the last whorl. Protoconch missing, 6\ post-nuclear whorls remaining in holotype, the only 

 adult specimen. The axials number about twenty on the early whorls. The whole surface is crossed by 

 subobsolete spiral cords too indistinct to be accurately counted but approximately twenty on the 

 penultimate. 



Height u*5 mm.; diameter 4-5 mm. 



Type locality. St. WS 766. North of Falkland Is. 45 ° 13' S, 59 56' 30" W, 18 Oct. 1931, 545 m. 

 The species resembles antarctica Smith, but is not so definitely sculptured and has a more massive 

 sutural carina. 



Family NATICIDAE 

 Genus Amauropsis Moerch, 1857 

 Type (s.d. Dall, 1909): Natica helicoides Johnson 



Hedley (191 6) diagnosed an Antarctic series of Naticoids as follows: 'There is an Antarctic naticoid 

 group which cannot be received by any of the above (i.e. Natica, Cochlis, Cryptonatica, Polinices, 

 Euspira, Cepatia, Mamillaria), or by other known extra-limital groups such as Cernina or Mammilla, 

 not discussed by Dr Dall. So far this amounts to about a dozen rather featureless species, all small, 

 mostly uniform olive buff in colour, four whorls, a slightly raised spire, a caducous epidermis, com- 

 paratively thin, unsculptured, except for incremental striae, without umbilical funicle or a callus pad at 

 the insertion of the right lip. Operculum corneous paucispiral.' 



Unfortunately, in nominating the Recent south-eastern Australian Natica beddomei Johnston as 

 genotype of his new genus Friginatica, Hedley has in effect deviated from his intention, for beddomei as 

 figured by Watson (1886, pi. 28, fig. 3) is a small solid shell with a channelled suture but apparently no 

 epidermis. 



Smith (1907) used the Arctic Recent genus Amauropsis for one of this Antarctic series, i.e. A. rossiana 

 Smith from ' Discovery' Winter Quarters, and since these shells fit this genus in a general way there is 

 no reason why at this stage of our knowledge Amauropsis should not be used. The genotype of 

 Amauropsis is a large shell (1-1-5 in.), thin, with channelled suture; umbilicus a narrow line; chalky 

 white, covered with a light yellowish brown epidermis (Tryon, 1886, p. 53, pi. 22, fig. 31). The 

 operculum is horny. 



There is no marked difference between the radula of the Arctic helicoides (Troschel, 1861, pi. 15, 

 fig. 6) (Fig. J, 41) and that of the Antarctic anderssoni Strebel, aureolutea Strebel and rossiana (Eales, 

 1923) (Fig. J, 43). Each has a tricuspid central tooth, a bifid inner marginal and a simple outer marginal. 



