1902.] SPONGES OP THE " SKEAT EXPEDITION." 213 



Sigmata 0-012-0'016 mm. ; centrangulated sigmata 0*016 mm. 

 Toxa : arms 0-025, 0-016 ; length 0-049 mm. 

 Pulau Bidang. 



10. EsPERELLA SULEVOIDEA, n. sp. (Plate XIV. figs. 8 & 9 and 

 Plate XV. fig. 10.) 



Sponge creeping, attached at intervals, the attached pai'ts 

 forming thin disks. 



The skeleton consists of shoi't stout fibres of styles rising from 

 the sui-face of support and almost at once bi'eaking up into 3 or 

 4 compact biunches which I'un to the dermal membi'ane, through 

 which they pass, their ends foiming little hispid patches on the 

 surface which are visible to the naked eye. The dermal mem- 

 brane contains a netwoi-k formed of compact multispicular fibres. 

 In the meshes of this main framework lie the various forms of 

 microscleres. The rosettes of anisochelfe are mostly confined to 

 the superficial parts of the sponge. 



Spicules : — 



Tylostyles, with but slisfhtly marked head, and with a peculiar 

 undulating outline : 0-360"x 0-012 and 0-360 x 0-006 mm. 



Sigmata 0-06-0-08 x 0-006 mm. 



Toxa 0-5-0-14 mm. 



Anisochelfe in rosettes, 0-05-0-06 mm. 



Anisochelfe scattered, 0-033 mm. ; 0-012 mm. 



11. BlEMMA DEMOCKATICA, n. sp. (Plate XV. fig. 9.) 

 Sponge growing on a Lamellibranch shell and forming very 



thin encrusting sheets. The microscleres ai'e in striking pre- 

 dominance over the megascleres, which might almost pass un- 

 noticed. The microscleres are sigmata of many sizes, ranging 

 from 0*01 to 0-08 mm. ; they are frequently fascicled, and in this 

 case they may be either linear or, as is more commonly the case, 

 they may be of the same thickness as solitary sigmata of the same 

 length. The few megascleres are tylostyles often bent luther 

 sharply just below the head, or sometimes with a second swelling 

 immediately succeeding the head. 



Tylostyles 0-18x0-0025, head -005; 0-26x0-06, thickness of 

 head -008 ; 0-56 x 0-006 mm., thickness of head 0-009 mm. 



Sigmata 0-08 x 0-003 mm. to O'Ol linear. 



I have included this species in the genus Biemma with some 

 hesitation. Possibly it ought to form the type of a new genus. 



Pulau Bidang. 



12. Desmacella portis Topsent, 



Besmacella fortis Topsent, Revue Suisse de Zoologie, iv. 1896-7. 



With this species from the Red Sea and Bay of Amboina are 

 identified two specimens difi'ering somewhat in external features. 

 Each is greyish in spirit, but has coloured the spirit in one case 

 violet, in the other pink. 



The chief difference between the specimens is in the size and 

 position of the oscula. In the violet-coloured specimen (which is 



