SPONGES FROM THE ABROLHOS ISLANDS. 495 
surface is a single, round, open vent, 1"5 mm. in diameter. Oolour in spirit 
light greyish brown ; texture hard and compact. 
The arrangement, form and size of the spicules are similar to those of the 
type specimen. 
Previously knoivn Distrihution. Cargados, Indian Ocean (Dench/). 
Register JSfo. and Locality. VI. 12 a, Sandy Isle. 
21. DoNATiA ROBUSTA [Bowevhank). 
Tethea robusta Bowerbank [1873]. 
Tethya globostellata Lendenfeld [1897]. 
Tethja cliftoni Ridley [1884]. 
Tethya ingalU Kirlipatrick [1900]. 
Donatia arabiea Topsent [1906]. 
Donatiajaponica var. albanemis Hentschel [1909J. 
Tethya lyncurium Kow [1911]. 
Donatia ingalli Deudy [1916 B]. 
Donatia globostellata Topsent [1918]. 
(See M. Burton [1923] MS.) 
There are three specimens in the collection, greyish white in colour, 
ranging from 20 to 26 mm. in diameter. The surface of each is only slightly 
tessellated. 
The skeleton consists of radially arranged bundles of typical strongyloxea 
which spread out beneath the surface in brushes; loose, radiallj' arranged 
megascleres lie between the bundles. 
Spicules : — (1) Strongyloxea ; measuring about 1"62 by 0*028 mm. 
(2) Spherasters ; these form a dense cortical layer ; they have a large 
centrum and short conical rays ; diameter about O'l mm. 
(3) Small asters ; with short rays which may either bear a crown of 
short spines or be beset with numerous small spines ; the total diameter is from 
0'012 to 0"016 mm. These are found in the cortex and the choanosome. 
(4) Small asters ; with long rays which may either end in a sharp point 
or be spined terminally. These are confined to the choanosome ; but there 
are many intermediate forms scattered through the sponge. 
This species is undoubtedly very closely related to Donatia lyncurium 
(Linnseus), from which it differs in the large size of the spherasters and the 
greater differentiation of the small asters. 
Previously known Distrihution. Red Sea [Row, lopsent) ; Indian Ocean 
(Dendy, Lendenfeld, Ridley, Kirkpatrick) ; Australia (Hentschel). 
Register Kos. and Localities. II. 11, Wooded Isle ; VI. 7, VI. 19, Sandy 
Isle. 
22. Donatia mcltistella (Lendenfeld). 
Tethya multistella Lendenfeld [1888]. 
Tethya multistella Hallman [1914]. 
This species is represented by one small, sub-spherical specimen, greyish 
white in colour, 12 mm, in diameter ; and a fragment of another, pale brown 
