Syno2Jsis of the Australian Calcarea Heteroc<ela. 85 



narrow, o})ei\ing on the dermal surface tlir(3Ugli narrow, 

 irregular chinks between the tufts of oxea. 



The skeleton is arranged as usual, the spiculatioii heing 

 as follows: — (1) Gastral quadriradiates; small, very irregu- 

 hirly and confusedly arranged, so as to form a dense though 

 not very thick cortex ; usually more or less strongly sagittal, 

 but very vai-iable in the proportions of the rays. The basal 

 ray varies from two or three times the length of the orals 

 to about the same length or even shorter ; it is straiglit and 

 conical. The oral i-a^'s are usuallj' slightly curved towards 

 one another, conical and sharp-pointed, averaging about 

 O'Oi by 0005 mm. at the base ; apical I'ay conical, very 

 slightly curved, sharply pointed, about O'Oo mm. long. 

 (2) Subgastral sagittal spicules, indistinguishable. (3) Tubar 

 triradiates, with rather short and stout, conical, sharp- 

 pointed rays ; the oral rays very widely extended, often 

 nearly at right angles to the basal, nearly straight, averag- 

 iiig about 084 mm. by 0-0U9 mm. at the base ; basal ray 

 varying from about the same length to considerably longer 

 than the orals, the disproportion being greatest at the 

 distal ends of the chambers. (4) Tubar quadriradiates, 

 differing from the foregoing in tlie development of a sliort, 

 stout, curved and sharply pointed apical ray ; abundant, 

 especially towards the gastral surface, where the tubar 

 skeleton becomes very irregular. (.5) Oxea, short, straight 

 oi- rather crooked, slender, tapeiing to a sharp point at the 

 proximal end and with the di.stal end swollen out into an 

 ovoid head, like that of a spermatozoon, length about Oiv, 

 thickness below the head 0007 mm., head nearh^ twice as 

 tliick. These spicules are arranged in XQvy dense tufts at 

 the dittal ends of the chambers and their thickened ends 

 form an almost continuous crust over the dermal surface of 

 the sponge. The whole skeleton is \evy dense and compact, 

 so that the texture of the sponge is very firm, as in 

 S. (jelatlnosuon, which it closely appi'oaches in spieulation. 



Locality. — St. Vincent's Gulf (coll. Adelaide Museum). 



15. Sycon compres^iim, auctorum. 



Graiitia compvessa, various authors {exj., Bowerbank). 



Sijcandra compressa, Hiieckel. Die Kalkschwamme, Vol. 

 11, p. 3G0. 



This common European species is recorded from Australia 

 both by von Lendenfeld and Carter, but 1 have never 



