IQI 
KEY TO THE IDENTIFICATION OF THE SPECIES OF Cephalodiscus. 
Polypides in a common cavity with numerous ostia (sub-genus 
Demiothecta), 
Width of branches 2mm. or less; colony diminutive ; 
plumes less than six pairs, 
Polypides black ; plumes four pairs, except in males, 
which have one pair only, 
seers sos Steen eeesrooeie. (Lbarmer, 1905). 
Polypides with black pigment on stolon only ; plumes 
MIVEMIIAIT Sep aut ices em a gracilis (Harmer, 1905). 
Width of branches 4 mm. or more ; plumes six pairs, 
Cavity of tubarium with smooth inner surface ; dis- 
tance from one branch to the next, about 
TO vant. bee 8 hodgsont (Ridewood, 1906). 
Cavity of tubarium incompletely sub-divided by 
ridges and partitions of irregular shape ; 
distance from one branch to the next, about 
ESIC dodecalophus (M’Intosh, 1882). 
Polypides in separate cavities, each with a single ostium (sub- 
genus Idtothecia), 
Polypides black ; plumes seven pairs, 
Colony massive, width of branch 15 to 25 mm. or 
more; peristomial tubes very short, each 
with a short blunt lip ; no spines, 
Bee gaes atuaaate as nigrescens (Lankester, 1905). 
Polypides not black ; plumes six pairs, 
Width of branch (including peristomes) about 12 mm.; 
peristomial tubes longer than their width, 
each with a short lip ; no spines, 
SATAN ary ta cg Rye ok ae ate levinsemt (Harmer, 1905). 
Width of branch 5 to 10 mm. ; peristomial tubes short 
or absent ; spines long and slender, simple 
Or forked tertces.: .gilchristt (new species). 
