SIDONOPS CALIFORNICA. 



23 



that these spicules are foreign to the sponge. The presence of minute anaclades 

 (exotyles) and the far greater reduction of the mesoclade-cladomes in Sidonops 

 alba (Kieschnick) Thiele seem, together with the differences in the dimensions 

 of the other spicules, sufficient for specific separation; and the more so as 

 Sidonops alba (Kieschnick) Thiele occurs near Ternate while the specimens 

 described above have been found on the opposite side of the Pacific Ocean, off 

 the coast of Lower California. The differences between these closely allied 

 species are given in the following table. 





Sidonops alba 



Sidonops californica 



Large choaiiosonial 

 amphioxes. 



2.5 mm. and more long; 30 /( thick. 



1.2-2 mm. long; 30-48 /( thick. 



Large choanosoinal 

 styles. 



similar to the amphioxes, but shorter 

 (?) 



shorter than the amphioxes; up to 

 55 /( thick. 



Small dermal styles. 



250 /(long; 5 /( thick. 



175-290 /(long; 3-7 /( thick. 



Minute microamphi- 

 oxes. 



absent. 



50 /(long; l/( thick; perhaps foreign. 



Phigiotriaenes. 



rhabdonie 2 mm. long; about 50 /( 

 thick; clades 450 /i long; clade- 

 angles a little over 90°. 



rhabdome 0.9-1.45 mm. long; 20- 

 78 /( thick; clades 160-400 /t long, 

 clade-angles 104-120°. 



Ordinary a\iatriapnc\s. 



rhabdome 2.5 mm. long; 14 /t thick; 

 clades about 20 /( long; clade-angles 

 44°. 



rhabdome long; 10-17 /t thick; clades 

 22-45 /(long; clade-angles 45-66°. 



Mesoclades. 



rhabdome 3 mm. long; 14 /( thick; 

 epirhabd SO /( long; 1-2 clatles 18- 

 21 /( long; clade-angles 84-102°. 



ihal^dome long; 6-15 /( thick; epi- 

 rhabd 45-125 /( long; 1-3 clades 

 20-42 /( long; clade-angles 102-118°. 



Minute anaclades 

 (exotyles). 



170 /i long and over; with 1-3 clades. 



absent. 



Large oxyasters. 



length of each ray 15-30 /(; without 

 centrum. 



6-20 rays; 22-43 /t in total diameter; 

 without centrum. 



Small sphaerasters. 



total diameter 8 /(. 



total diameter 4.5-9 /(. 



Sterrasters. 



110 /( long ; 90 /( broad. 



116-130 fi long; 97-105 /( broad; 

 70-90 /( thick. 



