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



Hymeniacidoyi (?) hyalina, n. sp. (PL XLV. figs. 6, Q>a, 66). 



Sponge massive, amorphous, encrusted by numerous foreign organisms ; represented 

 in the collection by two or three small, shapeless fragments, remarkable for their 

 transparent, hyaline appearance ; the largest one only about 19 mm. in diameter. 

 Colour in spirit, very pale, yellowish grey, transparent. Texture soft and spongy, 

 internally cavernous. Surface, for the most part encrusted by foreign organisms, where 

 visible fairly smooth. Dermal membrane very distinct, hyaline. Oscula (? rather large 

 and scattered). 



Skeleton. — (a) Dermal; consisting of tylostylote spicules thickly and quite irregularly 

 strewn through the dermal membrane, (h) Main; diffuse and irregular in the extreme, 

 with only very slight indications of fibres running vertically towards the surface ; 

 composed of loosely and irregularly disposed tylostylote spicules of various sizes. 



Spicules. — Megasclera; of one form only, viz., smooth, nearly straight tylostyli 

 (PI. XLV. figs. 6, Qa, 66), wdth distinct but not very large, subglobular heads ; sharply 

 and fairly gradually pointed at the apex. Size very variable, but not differing in such a 

 manner as to give rise to outside smaller and inside larger spicules as in the genus 

 Suherites ; the different sizes are throughout mixed up with one another ; the maximum 

 size is about I'l by 0"025 mm. 



It seemed very doubtful whether it was worth while to describe a new species on 

 such frftgmentary evidence, but it is interesting to come across a form whose spiculation 

 is almost exactly that of the genus Suherites, while the other characters, e.g., the arrange- 

 ment of the skeleton and the nature of the ectosome, are totally different. We doubtfully 

 place the species in the genus Hymeniacidon because we do not know what else to do 

 with it. 



Locality. — Off the south-west coast of Patagonia. Two or three fragments. 



Hymeniacidon (?) suhacerata, Eidley and Dendy (PI. XXXIX. fig. 4 ; PI. XL. 

 figs. 5, 5 a). 



1886. Hymeniacidon {?) suhaceratu, Ridley and Dendy, Ann. and Mag. Nat. Hist., ser. 5, 



vol. xviii. p. 478. 



Sponge (PI. XXXIX. fig. 4) massive; consisting of irregularly anastomosing trabeculfe, 

 which may be subcylindrical, or angular, or more or less flattened and expanded. The 

 largest specimen, taken as a whole, is about 88 mm. long by 62 mm. broad and 37 mm. 

 thick. Colour in spirit pale yellow ; the sponge is characterised also by a peculiar, waxy, 

 translucent appearance. Texture rather brittle and cavernous. Surface glabrous in 

 appearance, but rather harsh to the touch and very uneven. Oscula of fair size, mostly 

 near the summit of the sponge, having their margins flush with the general surface. 



