SPONGES.-HALLMANN. 2 I C 



In regard to skeletal structure and the incomplete differen- 

 tiation of principal and accessory spicules, this species agrees 

 with C. inanchorata (p. 206), C. cJathrata (p. 209), C. spicata 

 (p. 210), and C. costifera, sp. noA., and is perhaps sufficiently 

 closely related to the first-mentioned to be regarded as a 

 variety of it. It is strange that, although four of these species 

 have been previously described, their peculiarity in spiculation 

 has hitherto been overlooked. The five species constitute a 

 well-marked group characterised, as regards skeletal features, 

 not merely by (i.) the imperfect differentiation of the principal 

 and accessory megascleres, and (ii.) the participation of the 

 former in the echination of the fibres — for these features are 

 found also in otherwise quite different species^ — but also (iii.) 

 by the peculiar mode of disposition (obliquity relatively to the 

 axis of the fibre) of the principal spicules of the main fibres, 

 more particularly towards their outer extremities, and the con- 

 sequent "semi-plumose" or "spicate" character of these fibres ; 

 (iv.) by the absence of axial spicules from the connecting 

 fibres ; and (v.) by the relatively dense echination of the super- 

 ficial transverse fibres, chiefly or entirely on their outer aspect. 

 Another character which appears to be of common occurrence, 

 is the inclusion of auxiliary megascleres amongst the intra- 

 fibral spicules; this, however, is not shown by C. clathrata. 

 To the same group, in all probability, Clathria coppingeri, 

 Ridley,! Rhaphidophlus hispiuosus, Whitelegge,2 and Ophlit- 

 aspongia niembranacea, Thiele,^ also belong. This group of 

 species might be called, after one of its species, the spicata- 

 group — a name which also calls to mind one of its character- 

 istic features 



Clathria costifera, sp. nov. 

 (Plate xxxi., fig. 2; and fig. 44.) 



Sponge jlabelliforni, moderately thin, stipitate, with 

 radially corrugated surface. The dermal membrane, 

 oiving to the abundance of its contained, {auxiliary) spi- 

 cjdes, forms a ivhitish encrustation in the dry state. The 

 main skeleton is a close reticulation of well-developed 

 horny fibres. The fibral spicules {principal styli) — which 

 are absent from the connecting fibres — are arranged in a 

 disorderly fashion and, particidarly in the more super- 

 ficial parts of the sponge, often project far beyond, or are 

 situated upon, the fibre, in the manner of echinating spi- 

 cides. A gradational series of spicules of intermediate 



1 Ridley— Eeport Zool. Coll. of the "Alert," 1884, p. 445, pi. xl., flgs. F, F'; 



PL xlii., fig's, i, i'. 



2 Whitelegge— Austr. Mus. Mem., iv., 10, 1907, p. 503. 



3 Thiele- Fauna Chilensis; Zool. .Tahrb. Suppl. vi., Bd. iiL, Heft 3, 1905, 



p. 450, figs. 67a-e, 105. 



