134 
EURETE ERECTUM. 
SCOPULES OF THE DIFFERENT FORMS OF EURETE ERECTUM. 
A 
In Schulze’s type 
B 
In E. e. tubuliferum 
Wilson. 
C 
In E. e gracile 
Wilson. 
D 
In the specimens ex- 
amined by me. 
Dermal 
scopules 
Total length 200- 
600 n) 4-6 end-rays 
with pointed, re- 
curved spines and 
terminal tyle with 
larger spines on lower 
side. 
Two kinds. In one 
3-4 cylindrical end- 
rays, 40 by 2 n, with 
minute sharp dentic- 
ulations and small 
smooth terminal tyle; 
centrum distinct; 
shaft 200-240 by 4 fx. 
In the other 4-10 
end-rays, 60-100 by 
2-3 1±, with minute 
sharp denticulations 
and a terminal tyle 
5-8 ij. in diameter, 
sometimes with re- 
curved spines; shaft 
a little longer than 
in the other form, 6 ix 
thick. 
Two kinds. In one 
4 end-rays, 50-70 by 
4-6 ix, tapering dis- 
tally, with minute 
denticulations bas- 
ally, smooth distally, 
without tyle or a 
very small terminal 
tyle; shaft 300 by 
6-8 ix. In the other 
4-6 cylindrical end- 
rays, 70-100 by 3-5 ix, 
slightly roughened, 
with terminal tyle 
6-12 ix in diameter, 
and spines. Total 
length 600-700 ix. 
Total length 200- 
420 /x. 2 or 4, rarely 
3 end-rays. 20-76 by 
1-3.5 /x at the base, 
attenuated distally 
or cylindrical, the 
end pointed, rounded, 
or slightly thickened, 
densely covered with 
minute spines. Shaft 
3-6 ix thick. 
Gastral 
scopules 
Similar to the dermal 
but larger on the 
whole and with more 
divergent end-rays, 
these more frequently 
angularly bent. 
4-6 end-rays 70-80 m 
long, either smooth, 
2 fx thick at base, and 
thickened to 4 /x dis- 
tally, with terminal 
tyle 12 ix in diameter 
with recurved spines 
on the lower side; or 
cylindrical, with mi- 
nute denticulations, 
with terminal tyle 
8 ix in diameter; or 
transitions between 
these; shaft 300 by 
5 ix. 
3-6 end-rays, 100- 
120 ix long, either cy- 
lindrical, 4-5 ix thick, 
with terminal tyle, 
12 ix in diameter with 
recurved spines ; or 
12 ix thick at base 
and tapering distally, 
without terminal tyle ; 
or transitions be- 
tween these. Total 
length 0.6-1. 5 mm.; 
shaft 8-16 ix thick. 
Total length 0.6- 
1.18 ix. 3-6, usually 
4 end-rays, 75-133 
by 2-8 ix at base, 
thickened distally or, 
rarely, cylindrical. 
Densely covered with 
minute recurved 
spines, with semi- 
spherical terminal 
tyle 12-17 ix in diam- 
eter, with large re- 
curved spines below. 
Shaft at base 4-11 ix 
thick. 
the specimens examined by Schulze and Wilson and those described in this 
paper indicate that the former differ from the latter quite as much as the latter 
differ among themselves. This is particularly noticeable in that the former 
possess dermal scopules with only two end-rays, which are absent in the latter, 
and that the gastral pentactine-like pinule-derivatives of the former are much 
larger than the corresponding spinules of the latter. The general agreement of 
all these sponges, the localities from which they were obtained, and particularly 
the fact that the differences between them appear to be virtually confined to the 
superficial spicules, which are of course most liable to be influenced by the 
environment, make it very doubtful, however, whether they should be considered 
