i 5 6 DISCOVERY REPORTS 



tion. From the back, the canal bears a striking resemblance to the rostrum of the bivalve Cuspidaria. 



Colour dull white. Operculum normal, ovate-pyriform with a terminal nucleus. 



Height 13 mm. ; diameter 57 mm. (holotype, St. 42). 



Type locality. St. 42. Off mouth of Cumberland Bay, South Georgia, 1 Apr. 1926, 120-204 m. 

 St. 144. Off mouth of Stromness Harbour, South Georgia, 5 Jan. 1927, 155-178 m. 



This species belongs to a southern group comprising Trophon scolopax Watson from between 

 Kerguelen and Heard Islands, 150 fathoms, Trophon septus Watson, Royal Sound, 28 fathoms, 

 Kerguelen Island and Trophon acanthodes Watson from West Patagonia in 175-245 fathoms (all 

 figured by Watson, 1886, pi. 10). 



The dentition, operculum and protoconch, so far as can be judged by the available material, shows 

 no marked departure from those of typical Trophon. The abnormally long anterior canal is scarcely of 

 sufficient taxonomic importance to warrant even subgeneric separation of this group of species. 



Dentition. Fig. M, 89, p. 195 (St. 42). 



Subgenus Stramonitrophon n.subg. 

 Type : Trophon laciniatus Martyn 



This new subgenus is proposed solely on account of the dentition, which is quite unlike that of other 

 Trophons but bears a remarkable resemblance to the radula of the Thaisid genus Stramonita (see 

 Troschel, 1869, pi. 12, figs. 3-9). The central tooth has a broad, shallow, rectangular base with upturned 

 denticulate ends and three very large and tall main cusps. The middle one is slender and tallest and the 

 side ones broad, rendered bifid by a semi-detached cusp on the inner slope and bearing four denticles 

 on the outer slope. 



The protoconch is paucispiral as in typical Trophon, the operculum ovate with a terminal nucleus, 

 and the shell is fusiform with prominent lamellate axials. 



Apart from the anomalous dentition, there is nothing to distinguish laciniatus from a normal Trophon. 



Trophon (Stramonitrophon) laciniatus (Martyn) 



Buccimtm laciniatum Martyn, 1789, pi. 42. 



Fusus laciniatus (Gay) Hupe, 1854, p. 168. 



Trophon laciniatus Rochebrune & Mabille, 1889, p. 53. 



Trophon laciniatus Strebel, 1905 a, pi. 3, figs. 1-8. 



Trophon laciniatus Strebel, 1908, p. 37. 



Type locality. Strait of Magellan. 



St. WS 85. 8 miles S 66° E of Lively I., East Falkland Is. 25 Mar. 1927, 79 m. 



St. WS788. Between Falkland Is. and Patagonia, 45° 07' S,65°W to 45 07' S, 64°54'W, 13 Dec. 1931, 82-88 m. 



Range. Strebel (1904, loc. cit) records this species from many Magellan localities; Falkland Is., 

 25 m.; Burdwood Bank, 137-150 m. and South Georgia, 75 m. 



The South Georgia record, however, is probably based upon shackletoni paiicilamellatus n.subsp. 



I am not certain if the ' Discovery ' material is correctly placed in laciniatus, but certainly the St. WS 85 

 shell closely resembles Strebel's (1904) fig. 1, pi. 3, and the St. WS 788 shell his fig. 7, pi. 3. 



Dentition. Fig. L, 86, p. 194 (St. WS 788). The radula of a St. WS 85 specimen is identical. 



