222 SIDONOPS. 



Isops imperfecta (Bowerbank). 



SoLLAS, Rept. voy. "Challenger," 18SS, 25, p. 269. Lendenfeld, Ticrreich, 1903, 19, p. 97. 

 Geoilia impcrfecla Bowerb.vnk, Proc. Zool. soc. Lomloii, 1874, p. 299, plate 46, figs. 6-13. 



Massive tuberous. Dry: white. 



Amphioxes and amphistrongyles: 1.75 mm. by 39 it. Teloclodes: triaene, 

 diaene, or monacne; clades usually rounded terminally. 



Sphaerasters: rays slender, cylindrical, truncate; centiiim small; total 

 diameter 21 /(. Dermal sphaerasters: rays terminally divided into numerous 

 spines; centrum large; total diameter 12-19 //. Steirasters: ellipsoidal, de- 

 pressed, or cylindrical, 110 by 80 fi. 



? Southern Pacific. South Sea. 



Isops obscura Thiele. 

 Zoologica, 1898, 24, p. 6, plate 2, fig. 2; plate 6, figs. 2a-k. Lendenfeld, Tierreich, 1903, 19, p. 96. 



Irregularly massive. Dark brown. 



Amphioxes: 1.2-1.6 mm. by 15-40 fx. Plagiotriaenes: rhabdome curved, 

 1.25 mm. long; clades stout, 80-120 /« long; clade-angles large. 



Lai-ge thin-rayed oxyasters: rays slender, 20 p long. Small thick-rayed 

 oxyasters: total diameter 75 p. Oxy sphaerasters: diameter the same as in the 

 oxyasters. Sterrasters: spherical, 60 p in diameter. Steiroids: rare, similar 

 to the sterrasters but with much thicker rays. 



Northwestern Pacific. Japan. 



Isops soUasi Lendenfeld. 

 Descriptive catalogue sponges Australian museum, 18S8, p. 34. Tierreich, 1903, 19, p. 97. 



Cup shaped, peduncular, or lamellar. Brown. 



Choanosomal rhabds: 800 by 16 /(. Plagiotriaenes: rhabdome 1 mm. by 

 25 p; clades blunt 260 p long. 



Euasters: 16-30 p in diameter; smaller many-rayed and larger few-rayed to 

 be distinguished. Sterrasters: 48 p in diameter. 



Southwestern Pacific. East coast of Australia; Port Jackson. 



SroONOPS SoLLAS. 



Among the megascleres are regular triaenes. The tetraxon megascleres 

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

 dermal microscleres are asters. The afferents are cribriporal; the efferents 

 uniporal. 



