28 THE VOYAGE OF H.M.S. CHALLENGER. 



fibre. The fibre contains but little horny matter, is usually polyspiculous, and is 

 abundantly echinated, especially at the angles of the meshes, by tufts of outwardly 

 projecting spicules. The meshes are small, averaging only about 0'14 mm. in diameter. (6) 

 Main ; a very regular, well-developed, rectangularly-meshed reticulation of strong spiculo- 

 fibre ; the primary lines running vertically to the surface, and the secondary ones crossing 

 them at right angles (PI. XLVI. fig. 6). The fibre is polyspiculous (the primary lines 

 containing more spicules than the secondary), but though the spicules form a large 

 proportion of its bulk, there is a great amount of horny matter present which completely 

 envelops them ; thickness of fibre up to about 0'06 mm. 



Spicules. — Short, stout, slightly curved, sharply but very abruptly pointed oxea ; size 

 about 0-088 by 0-009 mm. 



The external appearance, the form and size of the spicules, and the great regularity 

 of the rectangular skeleton, are characters by which this sponge may be recognised. 

 Indeed, it is an unusually well-marked species. It differs from most Chalinine sponges 

 in the comparatively small proportion of horny matter in the spiculo-fibre, and is the 

 only known strictly encrusting species of the subfamily, although in their low crouching 

 growth, as well as in the skeleton arrangement and size of the S23icules, Chalina 

 finitima of Schmidt and Chalina limbata of Bowerbank make an approach to it. 



Locality.— Station 208, January 17, 1875 ; lat. 11° 37' K, long. 123° 31' E. ; Philip- 

 pine Islands; depth, 18 fathoms; bottom, blue mud. One specimen. 



Chalina sp. (a). 



A small fragment composed of short, cylindrical branches, about 4 mm. in diameter, 

 which we have been able to refer to no species known to us, and which is too imperfect 

 to render a recognisable specific description possible. It is characterised by a beautifully 

 reticulate surface, the fibres of the reticulation, as seen by the naked eye, standing out 

 as delicate raised veins, the meshes being triangular. On microscopical examination, the 

 meshes of this coarser reticulation are seen to be subdivided by much finer fibres into a 

 number of very small secondary meshes. The coarser fibres of the dermal reticulation 

 measure about 0-05 mm. in thickness, and contain a great many spicules ; the smaller ones 

 are usually only one spicule broad. The larger fibres of the main skeleton measure about 

 0*07 mm. in thickness. The spicules are very small and slender, slightly curved oxea, 

 measuring about O'l by 0-004 mm. 



Locality. — Cape York, Torres Strait ; 3 to 1 1 fathoms. 



Cfialina sp. (h). 



A single compressedly lobate specimen, 75 mm. in height by 25 mm. in breadth 

 near the top, and about 12 mm. thick. Colour in spirit dirty yellow. Texture 



