98 DISCOVERY REPORTS 



The species resembles M. refulgens Smith (1907) (Valvatella), from McMurdo Sound, 10-130 

 fathoms. Smith's species, however, is much smaller (5x5 mm.) and lacks the spiral grooves surrounding 

 the umbilicus. 



Margarella porcellana n.sp., PL V, fig. 2 



Shell small, uniformly white, polished and faintly iridescent within the aperture. Whorls 4*, 

 relatively slowly increasing, broadly convex above and more narrowly convex at lower third of whorl 

 height. Spire five-sixths the height of the aperture. Suture adpressed throughout, giving the ap- 

 pearance of a narrow submargining. Columellar callus broad with a sharply defined edge, concave 

 and completely covering the umbilical area. The species is close to steineni, but differs in having a higher 

 spire and adpressed false-margined sutures. Also, it lacks the pearly appearance of the exterior and the 

 intense iridescence of the interior, which features are so characteristic of steineni. 



Major diameter 8-o mm. ; minimum diameter 7-0 mm. ; height 7 mm. (holotype). 



Major diameter 8-5 mm. ; minimum diameter 6-7 mm. ; height 6-5 mm. (steineni, St. 145). 



Type locality. 



St. 1562. Off Marion I., 46 517' S, 37 56-5' E to 46 54-8' S, 37 53-8' E, 7 Apr. 1935, 97-104 m. 

 St. 1564. Off Marion I., 46 36-5' S, 38 02-3' E, 7 Apr. 1935, 108-113 m. 

 St. 1563. Off Marion I., 46 48-4' S, 37 49-2' E, 7 Apr. 1935, 113-99 m. 



Margarella antarctica (Lamy) 



Margarita antarctica Lamy, 1905, p. 481. 

 Margarita antarctica Lamy, 1907, p. 9, pi. 1, figs. 2, 3, 4. 

 Valvatella antarctica Melvill & Standen, 1907, p. 99. 

 Valvatella antarctica Lamy, 19110, p. 13. 



Dentition. Fig. G, 9, p. 189. 

 Type locality. South Orkney Is. 



St. 164. East end of Normanna Strait, South Orkneys, near Cape Hansen, Coronation Is., 18 Feb. 1927, 24-36 m. 



St. 179. Melchior I., Schollaert Channel, Palmer Archipelago, 10 Mar. 1927, 4-10 m. 



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). 



Range. Palmer Archipelago (' Discovery'), Wandel I. and Moureau I. (Thiele, 1912), Petermann I. 

 (Lamy, 191 1), South Orkneys (Lamy, 1905) and South Shetlands ('Discovery'). 



Subgenus Promargarita Strebel, 1908 

 Type (monotypy) : Promargarita tropidophoroid.es Strebel 



The genotype appears strikingly different from typical Margarella which has a smooth surface and 

 rounded whorls. Strebel's Promargarita tropidophoroides is biangulated by two heavy spiral keels, and 

 the entire surface is deeply incised with closely spaced spiral grooves. It is pointed out below, however, 

 that achilles Strebel has incised spiral sculpture both on the early whorls and surrounding the umbilical 

 area, but the rest of the shell is smooth. My new subspecies obsoleta has uniformly developed incised 

 spirals over the whole shell, but it is only weakly biangulate as also is achilles. All three are uniformly 

 brownish except for a white zone around the umbilical area and one or two narrow white bands in 

 place of the keels where these have been reduced to subangles. 



The radulae of both tropidophoroides and achilles show no essential differences from that of Margarella. 



Strebel's Promargarita is retained as a subgenus, since it expresses a localized spirally sculptured 

 trend in a genus that normally has smooth polished shells. 



