﻿SPONGES.-HALLMANN. o t - 



2 lo- 

 in regard to skeletal structure and the incomplete differen- 

 tiation of principal and accessory spicules, this species agrees 

 with ('. i\ianchorata (p. 206), C. clathrata (p. 209), C. spicata 

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

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

 \'ariety 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 

 tound 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 transxerse 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,! Khaphidophlus bispinosus, Whitelegge,^ and Ophlit- 

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

 species mig;ht be called, after one of its species, the spicata- 

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

 istic features 



Clathria costifera, .sp. tiov. 

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



Sponge llabelliforni, moderately thin, siipitaie, witJi 

 radially corrugated, surface. The dermal nioubrane, 

 owing to the abundance of its contained (auxiliary) spi- 

 cules, forms a whitish encrustation in the dry state. The 

 main skeleton is a close reticulatioji of well-developed 

 horny fibres. The fibral spicules (principal styli) — ivhich 

 are absent from the connecting fibres — are arranged in a 

 disorderly fashion and, particularly 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- 

 cules. A gradational series of spicides of intermediate 



1 Ridley— Report Zool. Coll. of the "Alert." 1884, p. 445, pi. xl.. figs. P, F'; 



PI. xlii., figs, i, i'. 



2 Whitelegge— Austr. Mus. Mem., iv., 10, 1907, p. 505. 



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



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



