TETRAXONIDA 313 



a sub-isodictyal reticulation of styli (often modified to incipient acanthostyli) ; styli of 

 main skeleton, often bearing a few spines at the base, 0-24 by o-oo8-o-oi8 mm. ; dermal 

 tornota, straight, with ends strongylote to subtylote, often minutely spined, o-i6 by 

 0-007 iTim.; chelae, 0-035 "^"^- chord. 



Remarks. The species may be distinguished from other Antarctic species of Myxilla 

 by the absence of sigmata. 



Genus Ectyodoryx, Lundbeck 



Ectyodoryx paupertas, subsp. nobile (Ridley and Dendy). 



Myxilla nobilis, Ridley and Dendy, 1886, p. 473 ; M. nobilis, vnr.patagonica, id., loc. cit., p. 473 ; 

 M. nobilis, var. bacillifera, id., loc. cit., p. 473; M. nobilis, id., 1887, p. 140, pi. xxvii, fig. 15, 

 pi. XXX, fig. 2; M. ?iobilis, var. patagonica, id., loc. cit., p. 142, pi. xxvii, fig. 13 ; M. nobilis, var. 

 bacillifera, id., loc. cit., p. 142, pi. xxvii, fig. 14; Stylostichon nobile, var. patagonicum, Topsent, 

 1913, p. 622; Ectyodoryx nobilis. Burton, 1929, p. 399. 



Occurrence. St. 157: South Georgia, 970 m. ; St. 158: South Georgia, 401-41 1 m.; St. 159: South 

 Georgia, 160 m.; St. WS79: Falkland Islands, 131-132 m.; St. WS82: Falkland Islands, 140- 

 144m.; St. WS83: Falkland Islands, 137-129 m.; St. WS86: Falkland Islands, i5i-i47m.; 

 St. WS 225 : Falkland Islands, 162-161 m. ; St. WS 239 : Falkland Islands, 196-193 m. ; St. WS 243 : 

 Falkland Islands, 144-141 m. ; St. WS 247 : Falkland Islands, 172 m. ; St. WS 249 : Falkland Islands, 

 166 m. 



Remarks. The five specimens in the collection show clearly that it is unnecessary to 

 maintain the varieties patagonica and bacillifera. It is quite evident that the species is 

 variable in so far as the characters of the spicules are concerned. The bases of the styli, 

 for example, may be simply irregularly tuberculate, or may bear a few spines, or they 

 may be crowded with numerous small spines. The tornota may be simply strongylote at 

 each end, or the ends may be slightly inflated, and in both cases a few small spines may 

 or may not be present. An important feature which Ridley and Dendy overlooked is the 

 diff'erentiation of the chelae into two categories, the larger being approximately twice the 

 size of the smaller. 



As has already been suggested by Ridley and Dendy (1887, p. 143) and Arnesen 

 (1920, p. 23), I propose to regard Myxilla nobilis and M. paupertas as forms of one 

 species, the former and its varieties constituting a subspecies distributed throughout 

 the South Atlantic and the immediately adjacent waters, and the latter as a subspecies 

 confined to the North Atlantic. The difference between these two subspecies consists 

 almost entirely in the larger size of the spicules and the slightly more profuse spining in 

 the styli of Ectyodoryx paupertas, subsp. typica, subsp.n. This subspecies includes, in 

 addition to the forms mentioned by Topsent (1904, p. 168), Anchinoe nobilis, Arnesen 

 (1920, p. 22). 



Distribution. Crozet Islands; Patagonia; off the mouth of the Rio de la Plata; 

 Burdwood Bank. 



