228 GEODIA. 



Sidonops nitida (Sollas). 



Proc. Roy. Dublin soc, 1SS9, 6, p. 277. Lendenfeld, Tierreich, 1903, 19, p. 104. 



Synops nUiiliis Hollas. Proc. Roy. Dublin soc, 1SS6, 5, p. 19S. Rept. voy. "Challenger," bSSS, 25, p. 2.31, 

 plate 22, figs. 1-lS. 



Lamellar, attenuated towards the margin. In spirit: faint browni.sli white. 



Amphioxes: 1.25 mm. by 26 /t. Orthoplagiotriaenes: rhabdome 1.07 nun. 

 by 28.7 /«; clades 183 /i long; cladome 358 /« broad, 50 pt high. 



Choanosomal oxyasters: usually' about seven, sometimes as few as two, 

 stout blunt rays with large spines; centrum small; total diameter, 43.4 /i. 

 Strongylosphaerasters: rays thick, terminally rounded; total diameter 13.5 /i. 

 Sterrasters: sjiherical, 51. G /< in diameter. 



Southwestern Pacific. East coast of Australia; Port Jackson. 



GEODIA Lamarck. 



Among the megascleres are regular triaenes. The tetraxon megascleres 

 are confined to the superficial part of the sponge and arranged radially. The 

 dermal microsderes are asters. The afferents are cribrijjoral, the efTerents 

 cribriporal. 



Forty-four species are known, twenty-nine of which occur in the Pacific 

 Ocean. 



SUMMARY OF THE SPECIES FOUND L\ THE P.VCIFIC OCEAN. 



.A, Fully developed triaene mesoproclades (proclades) present. 



Ao The large choanosomal astei-s are oxyastere, rarely strongylasters, never 

 acanthtylastei-s. 

 A3 With sphaerasters up to 90 /< in diameter. 



G. nux (Selenka). 

 B3 The largest sphaerastere under 60 /i in diameter. 



A4 With sphaerasters up to 31 fi in diameter, with very large centrum 

 and numerous very short and thick rays. 

 A5 The rays of the sphaerasters with large centi-um are conic. 

 G. eosaster (Sollas). G. globostella Lendenfeld. 

 B-, The rays of the sphaerasters with large centrum arc cylindrical, 

 tnincate, and bear terminal sj)ines. 

 G. distincta Lindgren. 

 B4 Without large sphaerastei-s with very large centnim and very short 

 ravs. 



