TETRAXONIDA 309 



Other Antarctic species, being a deep olive-green or greenish brown. The spicules of 

 the holotype are: styli 0-235 by o-oo8 mm., tornotao-22 by 0-005 mm-> and onychaeta, 

 not differentiated into two groups, 0-04-0-175 mm. In the present specimens the sizes 

 are: styli 0-21-0-22 by 0-007 nim., tornota 0-18-0-2 by 0-004-0-005 mm., and onychaeta 

 0-07-0-21 mm. 



Distribution. Falkland Islands. 



Tedania oxeata, Topsent. 



T. oxeata, Topsent, 1916, p. 169; 1917, p. 61, pi. iv, fig. 14, pi. vi, fig. 19; Burton, 1929, p. 441. 

 Occurrence. St. 170: Clarence Island, 342 m. 

 Distribution. Graham and Victoria Lands. 



Section MYXILLEAE 

 Genus Myxilla, Schmidt 



Myxilla mollis, Ridley and Dendy (Plate LV, figs. 1-4). 



Myxilla mollis, Ridley and Dendy, 1886, p. 471 ; M. spongiosa, id., loc. cit., p. 471 ; M. mollis, 

 id., 1887, p. 133, pi. xxvii, fig. 4; M. spongiosa, id., loc. cit., p. 134, pi. xxvii, fig. 3 ; Kirkpatrick, 

 1908, p. 28; Hentschel, 1914, p. 97, pi. vii, fig. 5; M. magna, Topsent, 1916, p. 168; id., 1917, 

 p. 56, pi. iii, fig. 4, pi. vi, fig. 9. 



Occurrence. St. 42: South Georgia, 120-20401.; St. 123: South Georgia, 230-25001.; St. 159: 

 South Georgia, 160 m. ; St. 175 : South Shetlands, 200 m. ; St. 181 : Palmer Archipelago, 160-335 "i- '> 

 St. WS 27: South Georgia, 106-109 "i-; St. WS 42: South Georgia, 198 m.; St. WS 76: Falkland 

 Islands, 205-207 m.; St. WS 79: Falkland Islands, 131-132 m.; St. WS 83 : Falkland Islands, 137- 

 129 m.; St. WS 84: Falkland Islands, 75-74 m.; St. WS 88: Falkland Islands, 118 m.; St. WS 99: 

 Falkland Islands, 251 m. ; St. WS 225 : Falkland Islands, 162-161 m. ; St. WS 239 : Falkland Islands, 

 196-193 m. ; St. WS 244 : Falkland Islands, 253-247 m. ; St. WS 246 : Falkland Islands, 267-208 m. ; 

 St. WS247: Falkland Islands, 172 m.; St. WS250: Falkland Islands, 251-313 m.; St. MS 71 : 

 South Georgia, 120-60 m. 



Diagnosis. Young sponge cylindrical or flabellate, with smooth, even surface ; adult 

 sponge massive, sub-spherical or massively flabellate with surface more or less conulose, 

 or thrown into low, rounded tubercles ; main skeleton, at all times, ranging from regu- 

 larly isodictyal to sub-isodictyal with triangular meshes, often irregularly confused; 

 dermal skeleton a tangential layer of tornota in young sponges, which is gradually lost 

 with maturity, tornota being then arranged in dermal brushes or else almost absent from 

 dermis ; megascleres smooth, straight or curved styli or, occasionally, subtylostyli with 

 long oval heads, with one or a few spines at base in young forms ; microscleres ancorae 

 spatuliferae and sigmata, both forms being very variable in size or even, occasionally, 

 separated into two or more categories. 



Remarks. The species is represented by twenty-one specimens which show that 

 the variations are of two kinds, due to (i) the fluctuating variations in size of spicule. 



