SYSTEMATIC 139 



Subfamily BUCCINULINAE 



Genus Chlanidota Martens, 1878 



Type (monotypy) : Cominella [Chlanidota] vestita Martens, Kerguelen Island 



The genus is restricted to the Antarctic region, with a known range extending over the Weddell, 

 Enderby and Victoria quadrants. Only one species, the genotype, extends to as far north as the 

 Antarctic Convergence. 



The shell is very thin and is covered with a pilose epidermis. Anterior canal truncated, deeply 

 notched, with a ridge-margined fasciole. Operculum disproportionately small for the size of the aperture, 

 irregularly ovate, horny, excentric, with the nucleus at the anterior margin (Figs. F and N, 129). 



The radula is very uniform ; it has a tricuspid central tooth with a broad excavated basal plate and 

 a tricuspid lateral on either side of it. Specific differentiation is most clearly shown in the respective 

 shapes of the central tooth. The tricuspid laterals have the central cusp weak and situated close along- 

 side the inner cusp suggesting bifurcation of the inner of two original cusps. However, the three lateral 

 cusps are now so stable a feature that Chlanidota is more naturally placed with the Buccinulinae than 

 with the Cominellinae. In fact Chlanidota, Neobuccinum and the next genus, Pfefferia, may well 

 represent a transitional stage between the short canalled Cominellids and the long canalled Buccinulids. 



Reference to the Buccinidae is even less appropriate as shown by radula and opercular characters as 

 well as from geographical considerations. 



Chlanidota vestita (Martens) 



Cominella [Chlanidota) vestita Martens, 1878. 



Chlanidota vestita Tryon, 1881, p. 201, pi. 79, fig. 391. 



Neobuccinum vestitum Watson, 1886, p. 216. 



Chlanidota vestita Smith, 1902, p. 203. 



Cominella [Chlanidota) vestita Martens & Thiele, 1903, p. 63. 



Cominella [Chlanidota) vestita Lamy, 1911a, p. 63. 



Type locality. Kerguelen Island, Subantarctic. 



Range. Subantarctic, Kerguelen I., 88 m. (Martens) ; Antarctic, Cape Adare, 24-26 fathoms (Smith). 

 I have been unable to check the Cape Adare record with material. 



Chlanidota pilosa n.sp., PI. VIII, figs. 29 and 30 



Compared with the South Georgian densesculpta, the Bouvet Island species is more globose, the 

 spire more depressed (telescoped) and the shoulder quite distinctive in being noticeably inrolled to 

 a more deeply incised suture. The sculpture also is more pronounced, consisting of less dense but 

 stronger spiral threads. 



Shell thin and fragile, white, covered with a light yellowish brown epidermis which develops dense 

 short bristles on all the spiral treads. Spire short, depressed, dome-shaped, 0-37 height of aperture. 

 Twenty-one narrow, crisp spiral threads on penultimate and about fifty-seven on body-whorl. Spiral 

 sculpture weakly concellated by closely spaced finer axial threads. In densesculpta there are from 

 thirty to thirty-six spiral threads on the penultimate. Anterior canal deeply notched. Fasciole well 

 defined by arcuate growth lines, but not ridge-margined above as in densesculpta. 



Height 25-5 mm.; diameter 20 mm. (St. 456, holotype /«7asfl n.sp.) 



Height 34-5 mm. ; diameter 24 mm. (holotype of densesculpta). 



Height 30-0 mm.; diameter 20 mm. (St. 1941, densesculpta). 



