SPONGES FEOM THE WESTERN COAST OF NORTH AMERICA. 119 



Chondrocladia Alaskensis. (Sp. IIOV.) 

 (Plate II., figs. 7, 7a— e.) 



Sponge (Plate IL, fig. 7), erect, borne ou a short stalk, showing a considerable variation 

 in external form, tlabellate, sometimes palmate and digitate, often irregularly lobate. Colour, 

 in spirit, dark brown. Texture, elastic, spongy. Dermal membrane, thin, not easily sep- 

 arated from the supporting fibres. Oseiila, numerous, from 1 to 3 mm. in diameter, occurring 

 on the sides and edges of the fan-shaiie(l and iialmate forms. In digitate specimens they 

 may be dispersed or ranged along the sides of the branches. In the irregularly loliate forms 

 the oscula are nearly always confined to the upper surfaces of the lobes (Plate IL, fig. 7), 

 when there may be man}- small oscula or a few large ones. Pores, in sets of three or four 

 between the brushes of the dermal skeleton ; average diameter 0-032 mm. 



Skeleton. — ((/) Main. Strong primary fibres of spicules crossed at right angles and at 

 rather irregular intervals by less robust secondary fibres, proceed to the surface and sub- 

 divide before the surface is reached, (b) Dermal, consisting of the outer ends of the jirimary 

 fibres which terminate in brushes at the surface ; the brushes support and project slightly 

 beyond the dermal membrane, which is sparsely supplied witli spicules lying horizontally in 

 it. A considerable amount of spongin is present. 



Spicules. — (a) 31egasclera, of two sizes. (1) Stout, slightly bent, smooth, somewhat 

 abruptly but sharply pointed styli (Plate IL, fig. 7a) with an average size of 0-262 by 0-019 

 mm. ; composing the main skeleton and the greater part of the dermal brushes. (2) Small, 

 slightly curved, rather bluntly pointed, smooth styli (Plate IL, fig. 7b) occurring in the 

 dermal membrane and supplementing the large styli in the dermal brushes ; average size, 

 0-144 by 0-008 mm. \b) Microsclera ; isochelse (Plate IL, figs. 7c, 7d;, large, with slightly 

 bent shafts bearing four or five large teeth at each end ; length, 0-091 mm. Small isochelse 

 (Plate IL, fig. 7e) occur in large numbers, about 0-032 mm. long ; probably an immature 

 stage of the large isochelse. Both forms are abundant in all parts of the sponge. In some 

 specimens numbers of spherical embryos 0-131 mm. in diameter were observed in the inner 

 parts of the sponge. 



This sponge possesses the characteristic isochelse of the genus, viz., equal ended spicules 

 having a curved shaft with a inimber of teeth at each end. It diflFers in outward form, in 

 which it has a considerable variability, from any hitherto described species of this genus, but 

 is easily recognized by its very characteristic spicules, as well as by its external shape. 



Distribution. — Behring Sea and North Pacific Ocean. 



Chondrocladia pulchra. (Sp. nov.) 

 (Plate IL, figs. 8, 8 a— d.) 



Sponge (Plate IL, fig. 8) erect, proceeding from a short thick stem, in most of the 

 specimens seen irregularly ramose ; branches somewhat compressed, anastomosing and 

 becoming broadly expanded in places ; in one specimen the anastomosing of the branches is 

 carried so far that the sponge takes the shape of a number of fan-shaped expansions, arising 

 either from the stout basal support or from some of those already formed. Colour, when 

 dry, a light brownish-j-ellow. Texture, very firm. Surface, rather uneven, slightly hispid. 

 Dermal membrane, very thin, delicate, spiculous. Oscula and pores have not been observed. 



