48 TETHYi. 



Tethya corticata, n. sp. 



8[)hencal sponges, 25-40 niillim. iu diameter, covered with conuli, always 

 attached by a small base ; root-like excrescences usually grow out from the 

 lower surface. The surface is irregular. Sharp, 2-3-5 millim. high conuli 

 are found on the upperside of the sponge ; the conuli are flattened, cylindrical, 

 or conic, and at the base 1 •5-2*5 millim. thick. A few oscula of irregular 

 outline and with a diameter of 2-4 millim. are found on the surface. Colour 

 of the cortex light red, flesh-colour in spirit. The interior dull white. 



Inhalant pores in the depressions between the high conuli lead into inhalant 

 canals which, extending centripetally, penetrate the cortex. Two or three join 

 to form a straight radial stem. These stem-canals are widened in a trumpet- 

 shaped manner at the proximal end ; in the centre they have a diameter of 0-08 

 millim., and they are as long as the cortex is thick, namely 2-2*5 millim. The 

 internal canals are larger than in most other Tethyce ; they are radial and 

 have an average diameter of 0-16 millim. 



Sl-eletoH. — The central mass of supporting-spicilles is spherical and has an 

 average diameter of 4 millim. ; the radiating bundles are 1 millim. thick ; 

 stellate microsclera are abundant, particularly in the cortex. — (1) Mer/asdera, 

 Styli 2 X 0-013 millim., straight, obtusely pointed at the outer end. The distal 

 ends of the centrifugal spicules project only 0-1 millim. over the surface. The 

 cortical spicules which surround the surface-tufts of the bundles are vertical 

 to the surface, and measure 0-4 x 0-006 millim. ; they are similar in shape to 

 the stvli of the interior. — (2) Stellate Microsclera. Of two kinds : — (A) Large 

 stellates, with conic rays : abundant in the cortex, diameter 0-06-0-08 millim. ; 

 each ray very regular, conic, 0*02-0-024 long, and at the base 0-006 millim. 

 thick ; these rays readily break off, and are often found scattered throughout 

 the cortex. (B) Small stellates, with cylindrical, slender, terminally thickened 

 rays : particularly abundant in the canal-walls ; diameter 0-016 millim. 



Geographical Distribution. — East coast of Australia : Port Jackson 

 (Ramsay). 



Tethya iissurata, n. sp. 



Irregularly spherical, more or less kidney-shaped sponges, with a flat base- 

 Body high, measuring 40 by 35 millim. From the base rootlets originate, 

 which attain a length of 20 millim. and more, are much and irregularly curved, 

 and have a thickness of 2-4 millim. The structure of the surface is very 

 remarkable ; protubei-ances are found on it, which give one the impression 

 that they do not belong to the sponge, and are separated from it by deep 

 incisions ; these protuberances widen centrif ugally, having the shape of broad 

 and low inverted cones ; 3 millim. wide and 1-2 millim. high ; their terminal 

 face is depressed, and i-ound the central depression a few spines are seen, like 



