R. W. H. ROW—REPORT ON THE SPONGES : NON-CALCAREA. 309 
purposes of description. Many of the spicules would go almost equally weil 
into either, such as those in which the ‘“ walking-stick head” is formed of 
more than one ray. 
Fig. 5.— Paratetilla eccentrica. Cortical trieenes, x 250. 
Others, again, do not come under either of these groups. Sometimes 
spicules can be found with a “head ” at each end of the long ray ; sometimes 
Fig. 6.—Paratetilla eccentrica. Cortical “ walking-stick” trizenes, x 250. 
all four actines are dwarfed and bulbous ; sometimes the spicule is reduced 
to two short rays, more or less malformed ; or it may even be represented 
by a single ray. It is worthy of note, however, that those rays which are 
