288 DISCOVERY REPORTS 



Plumocolumella myxillioides, sp.n. (Plate LIII, figs. 3, 4). 



Holotype. B.M. 28. 2. 15. 321. 



Occurrence. St. WS 79: Falkland Islands, 13 1-132 m.; St. WS 80: Falkland Islands, 152-156 m.; 

 St. WS 81 : Falkland Islands, 81-82 m. ; St. WS 83 : Falkland Islands, 137-129 m. ; St. WS 86 : Falk- 

 land Islands, 151-147 m.; St. WS 88: Falkland Islands, 96-127 m.; St. WS 243 : Falkland Islands, 

 144-141 m.; St. WS 246: Falkland Islands, 267-208 m.; St. WS 248: Falkland Islands, 210-242 m. 



Diagnosis. Sponge erect, arborescent with flattened anastomosing branches or sub- 

 lamellate ; surface smooth and even, bearing a conspicuous veining due to large subdermal 

 canals showing through a transparent dermis; numerous circular depressions, scattered 

 singly or in groups generally over surface, which probably bear both inhalant and ex- 

 halant apertures; colour, in spirit, yellow; skeleton, composed of irregular wisp-like 

 bundles of tornota running longitudinally through branches, often forming a dense axial 

 core, and bending towards surface or send off lateral branches to end in dermal brushes ; 

 tornota of main skeleton usually straight and smooth, with ends evenly and gradually 

 pointed, frequently hastate or mucronate, measuring 0-3 by o-oo6 mm. ; isochelae 

 arcuatae (.''), 0-03 mm. chord. 



Section MY GALEAE 



Genus Mycale, Gray 



Mycale magellanica (Ridley). 



Esperia magellanica, Ridley, 1881, p. 117, pi. x, fig. 5; E. cunninghami, Carter, 1882, p. 300, 

 pi. xi, fig. 17 ; Esperella magellanica, Ridley and Dendy, 1887, p. 67 ; Mycale magellanica, Thiele, 

 1905, p. 442; Mycale sp., id., loc. cit., p. 443, fig. 61: Mycale sp., Kirkpatrick, 1908, p. 37; 

 M. magellanica, Topsent, 1913, p. 632, pi. iv, fig. 4, pi. vi, fig. io;M.pellita, id., loc. cit., p. 633, 

 pi. V, fig. 2; M. antarctica, Hentschel, 1914, p. 58, pi. v, fig. 7; M. rossi, id., loc. cit., p. 59, 

 pi. V, fig. 8; M. magellanica, Dendy, 1924, p. 336; M. lillei, id., loc. cit., p. 337. 



Occurrence. St. 53 : Falkland Islands, 0-2 m. ; St. 55 : Falkland Islands, 10-16 m. ; St. 146 : South 

 Georgia, 728 m.; St. 175: South Shetlands, 200 m.; St. WS 73 : Falkland Islands, 121m.; St. 

 WS82: Falkland Islands, i40-i44m.; St. WS 83 : Falkland Islands, i37-i29m.; St.WS87: 

 Falkland Islands, 96-127 m.; St. WS 90: Tierra del Fuego, 82-81 m.; St. WS 177: South Georgia, 

 97 m.; St. WS 210: Falkland Islands, 161 m.; St. WS213: Falkland Islands, 249-239 m.; St. 

 WS 222: Falkland Islands, 100-106 m.; St. WS 225: Falkland Islands, 162-161 m.; St. WS 233, 

 Falkland Islands, 185-175 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. WS 247: Falkland Islands, 

 172 m.; St. WS 248: Falkland Islands, 210-242 m.; St. WS 249: Falkland Islands, 166 m.; St. WS 

 250: Falkland Islands, 251-313 m. 



Remarks. The synonymy of M. magellanica will be dealt with fully in a report, to be 

 published shortly, on the collections of the Swedish Antarctic Expedition. One point 

 only need be noted here in connection with this species, that a single specimen from 

 St. WS 222, otherwise typical, is entirely without microscleres. 



Distribution. Southern extremity of South America; Graham Land; Victoria 

 Land ; Wilhelm Land. 



