320 



DISCOVERY REPORTS 



Remarks. There are few species of Clathria in which microscleres are entirely absent, 

 and the present species is distinguished from all such hitherto described by the almost 

 complete absence of spines on the principal megascleres. In appearance it resembles 

 RaspaxiUa phakellimi, Topsent, but is distinguished from it by the absence of an axial 

 skeleton and plumose columns of spicules, as well as by the absence of the peculiar 

 acanthostyli in which the basal half is smooth. 



Genus Rhaphidophlus, Ehlers 

 Rhaphidophlus paucispiculus, sp.n. (Plate LVI, fig. i ; Fig. 30). 



Holotype. B.M. 28. 2. 15. 243. 



Occurrence. St. 160: Shag Rocks, 177 m.; St. WS 83 : Falkland Islands, 137- 

 129 m.; St.WS 84: Falkland Islands, 75-74 m-"- St. WS 109: Falkland Islands, 

 145 m. 



Diagnosis. Sponge massively flabellate, with tendency to give off 

 digitate outgrowths, to massively branching; surface uneven and 

 minutely conulose ; oscules and pores not apparent ; colour, in spirit, 

 light brown; main skeleton composed of irregular bundles of styli 

 running perpendicularly to surface or forming a confused reticulation 

 of spicules lying at all angles to each other; smaller styli, differing 

 from styli of main skeleton only in size, are scattered between fibres of 

 main skeleton and also form a dense dermal skeleton ; dermal skeleton 

 consisting of a tangential layer of smaller styli with brushes of similar 

 spicules situated immediately beneath and lying at right angles to it ; 

 styli of main skeleton smooth, slightly curved, o-54-o-7i by 0-024- 

 0-027 mm.; auxiliary styH, in dermal skeleton and scattered between 

 meshes of main skeleton, 0-24-0-31 by 0-006-0-009 mm. 



Remarks. The species appears to be a typical Rhaphidophlus, but 

 differs from all other species of that genus in the absence of echinating 

 acanthostyli and microscleres. There appears to be Httle difference 

 between the styli of the dermal skeleton and the auxiliary styli 

 scattered between the meshes of the main skeleton, and for this 

 reason they have been treated in the diagnosis as one form. There may 

 possibly be a slight difference in size, but if so it is hard to appreciate 

 this difference. Further, it is worth noting that intermediates between 

 the larger and smaller styli also appear to be present, but whether they 

 are very young forms of the larger styli or half-grown forms of the 

 smaller spicules is again difficult to determine. 



Fig. 30. Rhaphido- 

 phlus paucispicu- 

 lus, sp.n. Spicules 

 from a, main skel- 

 eton; b, dermis. 

 X 200. 



Genus Protoclathria, gen.n. 



Diagnosis. Clathrieae with skeleton composed of tylostyli and acanthostrongyla, 

 arranged in a triangular network; there is no dermal skeleton and microscleres are 

 absent. 



