SYSTEMATIC in 



Family TROCHACLIDIDAE 



Genus Trochaclis Thiele, 1912 



Type (monotypy) : Trochaclis antarctica Thiele 



Trochaclis antarctica Thiele 



Trochaclis antarctica Thiele, 1912, p. 192, pi. 11, fig. 29. 

 Trochaclis antarctica Hedley, 1916, p. 51. 



Type locality. Gauss Station. 



St. 1652. Ross Sea, 75 56' 2" S, 178 35' 5" W, 23 Jan. 1936, 567 m. 



St. 1658. Off Franklin I., Ross Sea, 76 09' 6" S, 168 40' E, 26 Jan. 1936, 520 m. 



Hedley (19 16) recorded the species from off the Shackleton Ice-shelf, 65 20' S, 95 27' E in 

 240 fathoms. 



Family CERITHIIDAE 



Genus Ataxocerithium Tate, 1893 



Type (o.d.) : Cerithium serotinum Adams, Tasmania 



The Magellan species pullum is referred to the above genus with some hesitation, since I know 

 nothing of either the opercular or the radula characters of the Tasmanian genotype. On shell features, 

 however, pullum is not dissimilar from serotinum. 



The operculum in pullum is ovate, slightly D-shaped, paucispiral, with the nucleus near to the inner 

 lower margin, which makes it a typical member of the Cerithiidae. The protoconch is very small and 

 slender, consisting of i| smooth papillate whorls followed by 1 \ whorls of brephic axials. The radula is 

 of the same general type as that of Cerithium except for the marginals, which have, in addition to their 

 normal bifid extremities, several well-developed cusps, which branch at right angles from the ventral 

 margin. There is only one of these side cusps on the inner marginal, but there are three on the outer 

 marginal. There is nothing comparable with these marginals in the Cerithiidae radulae figured by 

 Troschel (1858, pis. 9-12). 



Ataxocerithium pullum (Philippi) 



Cerithium pullum Philippi, 18456, p. 66. 



Cerithium caelatam Couthouy, 1849, p. 148, fig. \~j\a-d. 



Cerithium pullum Rochebrune & Mabille, 1889, p. H40. 



Cerithium pullum Strebel, 19056, p. 652, pi. 23, fig. \oa-d. 



Cerithium pullum Melvill & Standen, 1907, p. 105. 



Cerithium pullum Strebel, 1908, p. 47. 



Cerithium pullum Melvill & Standen, 191 2, p. 351. 



Dentition. Fig. I, 34, p. 191. St. WS 225. Protoconch. Fig. N, 102, p. 196. 



Type locality. Strait of Magellan. 



St. 51. Off Eddystone Rock, East Falkland Is., 7 miles N 50 E to 7-6 miles N 63 E, 4 May 1926, 105-115 m. 



St. 388. Off Tierra del Fuego, 56 19I' S, 67 ogf ' W, 16 Apr. 1930, 121 m. 



St. WS 72. Off north coast of East Falkland Is., 51 07' S, 57 34' W, 5 Mar. 1927, 79 m. 



St. WS 86. Burdwood Bank, 53 53' S, 6o° 37' W, to 53 54' S, 6o° 32' W, 3 Apr. 1927, 151-147 m. 



St. WS 97. North-west of Falkland Is., 49 S, 62° W to 49 01' S, 61° 56' W, 18 Apr. 1927, 146-145 m. 



St. WS 225. North-west of Falkland Is., 50 20' S, 62 30' W, 9 June 1928, 162-161 m. 



St. WS 239. North-west of Falkland Is., 51 10' S, 62 10' W, 15 July 1928, 196-192 m. 



St. WS 243. Between Falkland Is. and Point Santa Cruz, Patagonia, 5 1° 06' S,64° 30' W, i7July 1928, 144-141 m 



St. WS. 247. North of Falkland Is., 52 40' S, 6o° 05' W, 19 July 1928, 172 m. 



St. WS 250. North of Falkland Is., 51 45' S, 57 W, 20 July 1928, 251-313 m. 



