,g6 DISCOVERY REPORTS 



Remarks. The many attempts to establish a clear understanding of those species 

 of Halichondria, described by Bowerbank, in which the spiculation consists of 

 acanthostyli, tornota, anisochelae and bipocilla, have led to much confusion and a 

 multiplication of generic names. Gray {loc. cit.) divided them between two genera, 

 the first of which, Alebion, for Halichondria liytjdmam, Bowerbank, was preoccupied 

 {Alebion, Kroyer, 1863, Crustacea, fide Marschall, Nomeclator Zoologiciis, 1873). The 

 second, lophon, for Halichondria scandens, Bowerbank, is here retained. Later, Topsent 

 (loc. cit.) established the genus Pocillon for Halichondria hyndmani, which, as Dendy 

 {loc. cit.) pointed out, is probably a synonym of H. scandens. Pocillon becomes therefore 

 a synonym of lophon. At the same time, Dendy proposed to divide the species of lophon 

 into two groups, retaining the name lophon for the first and proposing the name lophon- 

 opsis for those species without echinating acanthostyli. My own investigations have 

 shown that some species are devoid of echinating acanthostyli during the early part of 

 their life, but possess them later, and that in those species in which they normally occur 

 these spicules may be only sparingly present or even absent from large tracts of the 

 sponge. As the presence or absence of echinating acanthostyli are the only features by 

 which a distinction between lophon and lophonopsis can be maintained, the use of the 

 latter name must be abandoned. Such a variable character obviously cannot be used 

 for purposes of generic distinction (cf. lophon chelifer). And finally, Burtonella is a 

 synonym of lophonopsis and is here included in the list of synonyms of lophon. 



lophon radiatus, Topsent. 



(For synonymy see Burton, 1929, p. 442, and 1931, pp. 512-518.) 



Occurrence. St. 123: South Georgia, 230-250 m.; St. 145: South Georgia, 26-35 m.; St. 170: 

 Clarence Islands, 342 m. ; St. 175 : South Shetlands, 200 m. ; St. 179 : Palmer Archipelago, 4-10 m. ; 

 St. WS 33 : South Georgia, 130 m.; St. WS 83 : Falkland Islands, 137-129 m. 



Distribution. Graham Land; Victoria Land; Wilhelm Land, 



lophon proximum (Ridley) (Plate LVII, figs. 1-13; Figs. 21-24). 



Alebion proximum, Ridley, 1881, p. 119, pi. x, fig. 8; lophon chelifer, Ridley and Dendy, 1886, 

 p. 349; /. pattersoni, id., 1887, p. 117; /. chelifer, id., loc. cit., p. 119, pi. xvi, fig. 3, pi. xvii, 

 figs. I, 3, 8; /. chelifer, Lambe, 1893, p. 30, pi. ii, fig. 7; id., 1896, p. 191; id., 1900, p. 23; 

 /. chelifer ostia-magna, Wilson, 1904, p. 143, pi. xx, figs. 2, 4, 10, 11, pi. xxiv, fig. i ; /. lamella, 

 id., loc. cit., p. 146, pi. XX, figs. 3, 7-9, 12, 13, pi. xxiv, figs. 2-4; /. lamella indivisus, id., loc. 

 cit., p. 149, pi. XX, figs. 14-16 ; /. chelifer, Thiele, 1905, p. 445, fig. 63 ; I.proximus {sic) reticularis, 

 Hentschel, 1914, p. 39. 



Occurrence. St. 6: Tristan da Cunha, 80-140 m.; St. 39: South Georgia, 179-235 m.; St. 42: 

 South Georgia, 120-204 ni.; St. 51 : Falkland Islands, 105-115 m.; St. 157: South Georgia, 970 m.; 

 St. WS 83 : Falkland Islands, 137-129 m.; St. WS 85 : Falkland Islands, 79 m.; St. WS 128: Gough 

 Island, 120-90 m.; St. WS 247: Falkland Islands, 172 m. 



Remarks. The Challenger specimens of /. chelifer exhibit a variability in spiculation 

 totally unsuspected from the description given by Ridley and Dendy. The lectotype. 



