SIDONOPS CALIFORNICA. 



23 



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

 (exotyles) and the far greater reduction of the mesoelade-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, oflf 

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

 species are given in the following table. 



