998 LIVERPOOL BIOLOGICAL SOCIETY. 
under the name /cionemia ponderosa, B., has, by further 
examination, turned out to be a Stelletta collingsi, B., or at 
least a variety of it. 
I have found in it all the different kinds of spicules which 
have been mentioned by Bowerbank, and more recently 
by Sollas,* and some other spicules in addition to those. 
The megascleres are—oxea 1°8 by 0'032 mm. ; orthotriena, 
the rhabdome of which measures 1°42 by 0'032 mm., and 
the cladi 0°105 by 0:028 mm. ; a few dichotrizna, the pro- 
tocladi of which measure in length 0°056 to 0°084 mm., and 
the deuterocladi 0°028 to 0°046 mm.; and a very few pro- 
trisena, rhabdome 0:40 mm., cladi0°086 mm. Both dicho- 
trizna and protrizena had not been mentioned by previous 
authors. The microscleres are—chiaster, 0°012 mm. in dia- 
meter, found only in the ectosome, just beneath the surface ; 
and oxyasters with a varying number of actines, found 
chiefly in the choanosome. It seems to be the rule that the 
larger the oxyasters are, the smaller is the number of their 
actines. I found that— 
4 radiated oxyasters measured 0°056 mm. in diameter 
6 is Bs 0:040__,, Ms 
8 55 Fe 0:032__,, i 
Besides those above-mentioned kinds of megascleres and 
microscleres I found an additional kind of spicule which 
I will call ‘‘ prionorrhabds” + (Pl. XIV., figs. 1 and 2). 
They are long and slender spicules, 0°40 by 0:002 mm., 
one end of which is profusely spined, the other and larger 
portion is smooth. The two extreme ends of the spicules 
are sharply pointed. I have found these prionorrhabds 
only in the ectosome, with their spined ends imbedded 
in it and the smooth ends projecting through the ecto- 
derm and penetrating into a calcareous sponge Sycan- 
* Sollas, loc. cit., p. 185. 
+ From mpiwy a saw. 
