216 MISS I. B. J. soLLAS OX THE [June 17, 



this conclusion I have seen Maas's paper (SB. Akad. "Wiss. 

 Munchen, 1900, pp. 553-569). Maas describes the origin of 

 spherasters from a paii- of small calthrops, and I am hence at a 

 loss to account for the globules vinless we may suggest that the 

 spherasters have more than one mode of oi-igin. 

 Great Redang. 



16. Tethya maza Sel. 



Tethya maza Selenka, Zeitschr. f. wiss. Zool. xxxii. p. 472, 

 pl.xxviii. (1879); SoUas, Yoy. H.M.S. ' Challenger,' vol. xxv. p. 440. 



Sponge hemisphei'ical. -The curved suiface is raised into low, 

 more or less hexagonal bosses. In the depression between the 

 raised areas are the pores leading into extensive, very i-egularly 

 arranged, intei'cortical cavities. 



The cortex is fibrous only in its innei- part. Osciila absent oi- 

 not distinguishable from the poi'es. Oolovn- in spirit greyish white. 

 Diameter of circular base 1 2 mm. The specimen is not gemmiferous. 



Megascleres : Strongyloxeas 1-20 x 0-025 ; 0-8 x 0-013 mm. 



Microscleres : Spherasters of many sizes, the maximum diametei- 

 is 0-056 ; centrum 0*025 mm. 



Chiasters abundant in the dermal membrane and occurring also 

 in the choanosome, 0-009-0-012 mm. 



Oxyasters 0-025-0-031 mm. ; actines slender, beset with spines so 

 low as to be mere roughenings. These microscleres often have only 

 6 rays lying in 3 axes at light angles ; in this case one pair of rays 

 is longer than the other two pairs, which are equal to one another. 



Pulau Bidang. 



17. Hymedesmia hallezi Topsent. 



Hymedesmia hallezi Topsent, Arch, de Zool. Exp. (3) t. viii. 

 p. 119 (1900). 



Sponge growing on a lamellibranch shell together with Samiis 

 anonymus. 



Besides the spicules of the vertical bundles which rest with 

 their oval heads in contact with the surface of support, other 

 more slender tylostyles lie horizontally. The microscleres are 

 distributed uniformly. They are asters of which the slender rays 

 are swollen at the tips. There is a distinct centi-um somewhat 

 sharply mai'ked off from the rays. They thus difier to a certain 

 extent from those of the type ; but as Topsent mentions that the 

 rays of the spherasters of H. hallezi sometimes end in a '■^ petit 

 houton non elai-gi," this difierence is probably unimpoi-tant. 



Vertical tylostyles 0-6-0-88 x 0-01 mm. 



Horizontal tylostyles 0-50 x 0-002-0-003 and 0-56 x 0-007. 



Pulau Bidang. 



18. Spirastrella incoxstans Dendy. (Plate XIV. fig. 3.) 



S'pirastrella inconstans Thiele, Studien iiber pacifische Spongien, 

 Zoologica, xxiv. ii. p. 10, pis. 1 & 5. 



A single specimen with the note : " a grey sponge from between 

 the stones between tide-marks. Loc. Pulau Bidang, R. Evans" 



