SPONGES FROM THE ABROLHOS ISLANDS. 481 
Genus AscoLEUCETTA n. gen. 
Leucascidpe with a well-developed dermal cortex densely packed with large 
and small triradiates and pierced by well-defined inhalant apertures guarded 
each by a fringe of hair-like oxea projecting radially inwards from 
within the margin. The elongated and much branched flagellate chambers 
are more or less radially arranged around the wide exhalant canals, which 
open by numerous oscnla. 
3. ASCOLEUCBTTA COMPRESSA n. sp. (PL 25. fig. 3 ; PI. 26. figs. 2, 3, 4, 5.) 
The sponge, which measures 25 mm. in height, 22 mm. in greatest width, 
and has an average thickness of 4 mm., forms an erect, compressed, irregular, 
more or less lobulated mass. The surface is smooth but uneven, and sieve- 
like in appearance owing to the presence of numerous small, circular, inhalant 
apertures, about 0"2 mm. in diameter, which are closely and uniformly scattered 
all over it. The oscula, which measure about 1 mm. in diameter, are arranged 
singly and are for the most part marginal. Colour in spirit light greyish 
brown ; texture firm and compact, rather hard. 
The inhalant apertures (PI. 26. fig. 5) pierce the well-developed dermal 
cortex, which is about 0'13 mm. in thickness, and lead into large, well- 
defined inhalant canals which run in between the flagellate chambers. The 
latter are much elongated and copiously branched ; they tend to be radiallj'' 
arranged round the larger exhalant canals, with their blind ends directed 
more or less at right angles towards the dermal surface (PL 26. figs. 3, 4). 
The chambers, whose walls are pierced by numerous prosopyles, open into 
wide exhalant canals which lead up to the vents. The collared cells are basi- 
nucleate and confined to the radial chambers, being absent from the exhalant 
canals. 
The skeleton consists of triradiates and quadriradiates, for the most part 
equiangular and equiradiate. The dermal cortex (PI, 26. fig. 5) contains 
numerous large triradiates arranged tangentially, intermingled with small 
triradiates which are packed in a dense feltwork around the margins of the 
inhalant apertures. These apertures are guarded by a fringe of hair-like 
oxea projecting radially inwards from the margin in small groups (PL 26. 
fig. 5). There are no large spicules in the interior of the sponge, small tri- 
and quadriradiates being scattered closely but irregularly in the walls of the 
radial chambers and exhalant canals, the facial rays lying tangentially, 
while the slender apical rays of the quadriradiates project into the chambers 
and into the exhalant canals. 
Spicules : — (1) Large triradiates (PL 26. fig. 2 a) ; with conical, straight 
or slightly crooked, gradually or sometimes rather abruptly sharp-pointed 
rays, measuring about 0"35 by 0'052 mm. 
(2) Small triradiates (PL 26. fig. 2 b) ; with straight, conical, bluntly 
pointed rays, measuring up to 0'14 by 0-03 mm. All the triradiates are 
LINN. JOURN. — ZOOLOGr, VOL. XXXV. 35 
