General History of the Marine Polyzoa. 365 
clothe throughout their whole length; they are disposed 
somewhat irregularly in whorls. The basal enlargements are 
closely packed together, and almost conceal the surface of the 
stem. ‘There is little branching; near the base the stem 
divides into two principal shoots, which give off laterals occa- 
sionally, but there is no definiteness in the plan of the 
ramification. ‘lhe whole surface of the tubes is finely lineated 
longitudinally. A very marked character of the species is 
the obliquely truncate extremity of the tube, which is pro- 
duced on one side into a strong spike-like projection. To- 
wards the base the stem gives off a large number of chitinous 
fibres, which torm a kind of adherent disk. 
The whole structure recalls very forcibly one of the Tubu- 
larian Hydroids. 
Group Heroprocra. 
Suborder CTENOSTOMATA. 
Family Flustrellide. 
FLUSTRELLA, Gray. 
Flustrella hispida, Fabricius, form cylindrica. 
(Pl XUV. figssd; Lat) 
Zoarium erect, much branched; stem and branches cylin- 
drical, composed of rather firm chitinous material. Zowcta 
disposed round the cylinder in six linear series, those of the 
neighbouring series alternating, large, regularly ovate, convex 
in front; surface smooth, round the margin a large number 
(15-18) of tapering acuminate spines, with an enlarged base, 
which bend inward over the front wall, but without meeting ; 
orifice close to the upper extremity of the cell, bordered above 
and below by a *' 1 horny rib; immediately above it a few 
(usually three) erect spinules; numerous large spines, 
springing from a kind of boss, scattered over the interspaces 
between the cells. 
Loc. Port Phillip Heads (J B. Wilson). 
Lange. Northern and Arctic seas, Britain, France (S.W.). 
This is a very remarkable form, and for some time I was 
quite disposed to regard it as a distinct species ; but a careful 
examination of the cell has convinced me that in this essential 
element of the structure there are no characters to separate it 
from the common /. hispida of our English coasts. ‘The 
difference in habit and external appearance, striking as it is, 
has a parallel in many other cases, and is merely varietal. 
