SPONGES FROM THE ABROLHOS ISLANDS. 491 
The skeleton, which agrees closely with that of Hentsehel's South-West 
Australian specimen, consists of radially arranged bundles of plagiotrisenes 
and oxea ; in the deeper parts there is less regularity. The spicules resemble 
closely those of the type in size and appearance. 
Previously known Distribution. Sharks Bay, S.W. Australia [HentscheV). 
Register No. and Locality. VI. 8, Sandy Isle. 
14. Stelletta debilis Thiele. 
Stelletta debilis Thiele [1900]. 
Stelletta debilis Lendenfeld [1903J. 
The single complete specimen is sixb-spherical in shape, measuring 15 mm. 
in diameter, There is a single oval osculum. 2 mm. long and 1 nmi. broad, 
near the point of attachment of the sponge to a piece of rock. Inhalant 
fiores are thickly scattered all over the slightly roughened surface between 
the cladi of the triaanes. Colour in spirit light brown ; texture firm and 
compact, but compressible. 
There is a slightly fibrous cortex, and the skeleton is radially arranged and 
quite typical. 
Spicules : — (1) OrthotriaSnes ; shaft straight or nearly straight, tapering 
gradually to a sharp point, measuring 1'35 by 0026 mm. ; cladi sharply 
pointed, recurving at once so as to extend at right angles to the shaft, 
measuring 0"i6 mm. in length. 
(2) Anatrisenes ; these frequently project beyond the surface of the 
sponge ; shaft long, slender, slightly curved, measuring 1'3 by O'Olo mm. ; 
cladi well developed and markedly recurved, measuring 0"052 mm. in length. 
(3) Oxea ; fusiform, usually carved, sharp-pointed, measuring 1"1 by 
0"02 mm.; these are most abundant in the deeper parts of the sponge. 
(4) Oxyasters ; with 6 to 10 slender, sharp-pointed rays and no distinct 
centrum; diameter 0'017 mm.; these are scattered sparsely throughout 
choanosome and ectosome. 
Previously known Distribution. Ternate [Thiele). 
Register No. and Locality. II. 16^ Wooded Isle. 
15. Stelletta siGMATRiiENA i>«?n(^eji/(?Z£^ [1906]. 
There are two small, complete specimens, sub-spherical in shape, 12 and 
8 mm. in diameter respectively. Inhalant pores, visible with a lens, are 
scattered evenly over the suiooth surface. Each specimen has one minute 
oval osculum lying in a slight depression. Colour in spirit buff. 
The skeleton consists of radially arranged oxea and trisenes, not concen- 
trated into bundles. Just beneath the surface the cladi of the trisenes form 
a sharply-defined layer ; their shafts pierce the region of the chones, which 
is cladome-free. In the choanosome are radially placed anatrisenes, 
orthotrisenes in various stages of development, and less regularly arranged 
oxea. 
