94 DISCOVERY REPORTS 



Photinula coerulescens Pilsbry, 1889, p. 278, pi. 44, figs. 18, 19. 



Photinula coerulescens Strebel, 1905, p. 140, pi. 5, figs. 25 a, b, 27a, b and 30. 



Photinula coerulescens Strebel, 1908, p. 71, pi. 6, fig. 93a, b. 



Photinula taeniata coerulescens Melvill & Standen, 1914, p. 116. 



Dentition. Fig. H, 24, 190. 



Type locality. Strait of Magellan. 



St. 51. Off Eddystone Rock, East Falkland Is., 4 May 1926, 115 m. 



St. 55. Entrance to Port Stanley, East Falkland Is., 2 cables S 24 E of Navy Point, 16 May 1926, 10-16 m. 



St. 56. Sparrow Cove, Port William, East Falkland Is., i\ cables N 50 E of Sparrow Point, 16 May 1926, 

 io|-i6 m. 



St. 1230. 67 miles N 62° W from Dungeness Lt., Magellan Strait, 23 Dec. 1933, 27 m. 



St. WS 79. Between Falkland Is. and Patagonia, 51 01' 30" S, 64 59' 30" W, 13 Mar. 1927, 132-131 m. 



St. WS 80. Between Falkland Is. and Patagonia, 50 57' S, 63° 37' 30" W, 14 Mar. 1927, 152-156 m. 



St. WS 217. North-north-west of Falkland Is., 47 06' S, 62° 12' W, 3 June 1928, 116-114 m. 



St. WS 764. Between Falkland Is. and Argentina, 44 38' 15" S, 6i° 58' 30" W, 17 Oct. 1931, 1 10-104 m - 



St. WS 775. Between Falkland Is. and Argentina, 46 44' 45" S, 63° 33' W, 2 Nov. 1931, 115 m. 



St. WS 782. North of Falkland Is., 50° 29' 15" S, 58 23' 45" W, 4 Dec. 1931, 141-146 m. 



St. WS 816. Between Falkland Is. and Patagonia, 52 09' 45" S, 64° 56' W, 14 Jan. 1932, 150 m. 



St. WS 817. Between Falkland Is. and Patagonia, 52 23' S, 64 19' W, 14 Jan. 1932, 191-202 m. 



St. WS 834. Off Santa Cruz, Patagonia, 50 18' 45" S, 67 44' W, 9 Feb. 1932, 27-38 m. 



St. WS 836. Off Patagonia, 53 05' 30" S, 67 38' W, 3 Feb. 1932, 64 m. 



St. WS 854. Off Patagonia, 45 16' S, 64 25' W, 22 Mar. 1932, 97 m. 



St. WS 869. Between Falkland Is. and Patagonia, 52 15' 30" S, 64 13' 45" W, 31 Mar. 1932, 187-0 m. 



Range. Southern Argentina to Tierra del Fuego and Falkland Is., 0-202 m. 



A handsome, depressed, smooth, pale, opalescent shell with a few conspicuous heavy spiral bands of 

 purplish brown to dark blue, often with subsidary spirals of green and grey. 



Genus Photinastoma n.g. 

 Type : Trochus taeniatus Wood 



The Falkland Islands taeniatus is very similar in appearance to the genotype of Photinula, but study 

 of the radula and epipodial characters shows that although they are both derivatives from Calliostomid 

 stock they are sufficiently distinct from each other to warrant generic separation. That taeniatus is not 

 a typical Photinula has been pointed out already by Dall (1889a, p. 344), who wrote: 'This species is 

 referred to Photinula by H. & A. Adams, but appears to be simply a smooth Calliostoma. There is no 

 umbilical callus as in Photinula coerulescens. . . ', etc., and by Strebel (1908, p. 71), who segregated it 

 from Photinula s.str. under ' Gruppe Calliostoma-Photinula Strebel '. This hyphenated combination has 

 been cited as of nomenclatural status by Neave (1939, p. 535), but it seems very clearly indicated that 

 Strebel did not intend this. The manner of presentation of subgenera in this same work of Strebel's 

 proves this, i.e. p. 74 'Gruppe Promargarita n.subg.' The question remains, that notwithstanding 

 Strebel's intention, does the entry fulfil the then existing requirements for a new name? The mere 

 hyphenating, without alteration, of two valid generic names, is apparently not covered by the rules, and 

 in my opinion does not amount to the proposition of a new genus or subgenus. 



Study of the dentition and epipodial fringe in taeniatus and coerulescens confirms that although they 

 compare in a general way with Calliostoma there are sufficient differences between them to warrant 

 separation. 



In Photinastoma taeniata the radula is almost identical with that of the Magellan Calliostomids. Also 

 it has four epipodial tentacles as in certain Californian and New Zealand Calliostomids, but not as in the 

 English genotype, which has three. Features of the taeniata radula, which are common to the Magellan 



