SYSTEMATIC 153 



This species stands nearest to geversianus, from which it differs in being more elongate and in having 



the lamellae produced into hollow spines. Also the surface spiral striations are not present in geversianus, 



which is white with the interior of the aperture often diffused with brown. 



Dentition. Fig. L, 83 , p. 194. The central tooth has a broad, shallow, arched, basal plate, bearing three 



large triangular cusps, middle one tallest, and two very weak intermediate denticles which are situated 



in the troughs, not offshoots from the outer cusps as in geversianus. 



Trophon scotianus n.sp., PL IX, figs. 48, 49 



Shell rather large, thin, light buff; sculptured with elevated, coronated, thin lamellae and a surface 

 pattern of low, rounded, spiral cords. Post-nuclear whorls five, plus a minute, smooth, papillate 

 protoconch of 1 \ whorls, the apex oblique and inrolled. Spire o-6 height of aperture plus canal. Axial 

 sculpture of very prominent, thin lamellae, produced into erect coronated processes on the shoulder 

 and extending over base to neck of canal, which is rendered prominently scaly by successive terminals 

 of labial varices. Axials six per whorl. Spiral sculpture of rather broad, low, rounded, spiral cords with 

 a narrow thread in each interspace. Labial varix broad, expanded and recurved, evenly arcuate right 

 to the shallowly sinused termination of the anterior canal. Operculum irregularly ovate, with terminal 

 nucleus. 



Height 34 mm. ; diameter 24 mm. (holotype). 



Type locality. St. WS 27. Off South Georgia, 53 55' 00" S, 38 01' 00" W, 19 Dec. 1926, 107 m. 

 (holotype, sole example). 



Dentition. Fig. M, 88, p. 195. The central tooth resembles that of echinolamellatus in having an 

 arched base and three triangular main cusps, but the intermediates are better developed. 



The species differs from shackletoni paucilamellatus in having fewer axial lamellae, well-developed 

 spiral sculpture, the labial varix extending to the end of the anterior canal, and in being coloured. 



Trophon shackletoni paucilamellatus n.subsp., PI. IX, fig. 52 



Shell moderately large and thin, white, with a short spire, long canal and prominent sculpture in the 

 form of a few wide, recurved, thin, smooth lamellae which rise high above the whorls and coronate the 

 spire. Whorls five, including a small, smooth protoconch. Axial lamellae twelve on the first post- 

 nuclear whorl, but reduced to eight on both the penultimate and the body-whorl. The lamellae vary 

 between seven and ten on the last two whorls in examples from other South Georgian stations. Surface 

 of shell smooth. Spire half the height of the aperture plus canal. Canal long, slightly reflexed and 

 recurved. 



Height 31 mm.; diameter 21 mm. (holotype, St. 148). 



Type locality. St. 148. Off Cape Saunders, South Georgia, from 54 03' S, 36 39' W to 54 05' S, 

 36 36' 30" W, 9 Jan. 1927, 132-148 m. 



St. 27. West Cumberland Bay, South Georgia, 3-3 miles S 44 E of Jason Lt., 15 Mar. 1926, 100 m. 



St. 140. Stromness Harbour to Larsen Point, South Georgia, from 54 02' S, 36 38' W to 54 11' 30" S, 



36 29' W, 23 Dec. 1926, 122-136 m. 

 St. 144. Off Stromness Harbour, South Georgia, from 54 04' S, 36° 27' W to 53 58' S, 36=26' Vv, 5 Jan. 



1927, 155-178 m. 

 St. 159. Off South Georgia, 53° 52' 30" S, 36° 08' W, 21 Jan. 1927, 160 m. 



St. 363. 2-5 miles S 8o° E of south-east point of Zavodovski I., South Sandwich Is., 26 Feb. 1930, 329-278 ™. 

 St. WS 33. Off South Georgia, 54° 59' S, 35° 24' W, 21 Dec. 1926, 130 m. 

 The species shackletoni Hedley (191 1) is found from seven to twenty fathoms off Cape Royds, in 



the Ross Sea on the opposite side of the Antarctic Continent. 



14-2 



