84 
an obstruction ; there they rest, and if the situation sn ,ts ' 
they fix themselves, if not they move on in the same mann 
to some other spot. If the change be only for a s ' ,f > ^ 
distance, as from one part of the leaf to another, they bet*^ 
their campanulate rims and bring the tentacula in 
with the fucus, and by them adhere to it; the foot-st® 
is then loosened, thrown forward, and twirled about, * 
it meets with a place to suit it; it is then fixed and the te ' 
tacula are loosened, and in this way they move from one sp ^ 
to another. They sometimes also move like the Actinias by 
gliding motion of the stalk. _ , 9 
In taking their prey they remain fixed, with their tentac 
expanded, and if any minute substance comes in contact wl 
any of the tufts, that tuft contracts, and is turned to 
month, while the others remain expanded watching for P re -j 
The differences between this and Dr. Johnston’s speoiw 6 
are as follows. The brown glandular bodies ot the free 
proceed from the tentacula in this, while in Dr. J.’s there 
a slight distance between them ; this may arise Iron) 1 
advanced stale of the ova in my specimens. In this the cb® 1 ( * 
of glands from the tentacula unite in pairs at three-fourth ® ^ 
the length of the body ; in the others they proceed singly 
the base. In this, the footstalk is distinctly separate from 
campanulate rim, in Dr. Johnston’s it is said to ho sc**’ 
and there is no distinction between the base and the o ttJ ' 
part. The peduncle, or foot, terminates in a flat, suck®, 
like expansion while in the other, both in the figures # 
description, it is absent. These characters have not be 
observed in a single specimen only, but in scores, and o' 
therefore be considered permanent variations or characters* 

SUB CLASS II. 
MOLLUSCAN ZOOPHYTES. , 
Body non-contractile, and non-symtnetrical ; mouth 
anus separate ; gemtniparous and oviparous. 
ORDER IV. 
ASCIDIOIDA. 
In the Ascidian Zoophytes, the Ciliobrachiata of . a t j fl n 
we shall observe a very great advance in the compm^ g f 
of the anatomy of the polype. Though possessing 
the external characters of the Hydra, and in its oecon 
and fabrication of its habitations also similar; yet we s 
