TETRAXONIDA 333 



Plicatellopsis arborescens, sp.n. (Plate LVI, fig. 5; Figs. 36 b, 37 h). 



Holotype. B.M. 28. 2. 15. 388. 



Occurrence. St. WS 83 : Falkland Islands, 137-129 m. ; St. WS 243 : Falkland Islands, 144-141 m. 



Diagnosis. Sponge erect, dichotomously branched; surface even, minutely hispid; 

 texture firm, compressible, friable; oscules and pores not apparent; colour, in spirit, 

 brown; skeleton an irregular reticulation of large styli giving off fibres which run 

 vertically to surface ; special dermal skeleton of bundles of small styli associated with 

 outermost ends of ascending main fibres ; large styli, slightly curved, 0-65 by 0-025 "^'^^ "> 

 small styli, straight or slightly curved, 0-28 by 0-007 ^^• 



Remarks. The skeleton is rather confused, its plan being obscured by the abundance 

 of isolated spicules scattered between the main fibres. The small styli are chiefly con- 

 fined to the dermis although a few, not in bundles, are to be seen scattered between 

 the meshes of the main skeleton. There is no visible spongin. 



The species differs from P. expansa, Thiele (Figs. 36 a, 37 a) in the external form and 

 in the absence of any tylostyli. 



Plicatellopsis flabellata, sp.n. (Plate LVI, fig. 6; Figs. 36 c, 37 c). 



Holotype. B.M. 28. 2. 15. 726. 



Occurrence. St. WS 84: Falkland Islands, 75-74 m. 



Diagnosis. Sponge irregularly flabellate, somewhat plicated; surface minutely 

 tuberculate, markedly hispid; texture soft, friable; oscules and pores not apparent; 

 colour, in spirit, brown; internal skeleton a confused mass of tylostyli, crossing 

 each other at all angles, from which irregular fibres run vertically to surface; special 

 dermal spicules in form of small styli; with long, slender tylostyli lying between 

 ascending fibres of main skeleton; tylostyli of main skeleton usually much curved, 

 0-4 by 0-014 mm. ; small styli of dermal skeleton, 0-2 by 0-003 rnin-! long, slender, 

 flexuous tylostyH, 2-0 by o-oi mm. 



Remarks. There is a marked relation between this species and P. expansa, Thiele 

 (cf. Figs. 34 a, 35 a), and P. arborescens, sp.n., but it differs from both in external form, 

 in the disposition of the skeleton and in having tylostyli in the main skeleton and small 

 styli for dermal spicules. 



Genus Bubaris, Gray 

 Bubaris vermiculata (Bowerbank). 



(For synonymy see Dendy, 1924, p. 351.) 

 Occurretice. St. 6: Tristan da Cunha, 80-140 m.; St. 283 : Gulf of Guinea, 18-30 m. 

 Distribution. Throughout Atlantic Ocean ; Kerguelen ; New Zealand. 



D VI 13 



