OF PLUMULARIA BULLATA. 305 
The marine plants which were collected during the last 
Arctic Expedition under Captain Pakey, were consigned 
to the care of Dr Hooker, for examination. There were 
a few zoophytes among them, which that distinguished 
botanist requested me to name. Though they were all 
found on the surface of the sea, about the middle of Hud- 
son's Strait, 29th July 1821, they were, with few excep- 
tions, such as Ellis has described, as inhabitants of our 
I own shores, differing, however, somewhat in habit. Among 
the Sertulariadae, one occurred which, from the preceding 
description, seems to be new, and the structure of which 
serves to throw considerable light on the physiology of the 
tribe. The drawing, which is now transmitted, will serve 
to exhibit the different stages of its growth. (Plate IX.) 
Judging from the structure of the whole specimen, there 
seems to be ground for entertaining the belief, that each 
branch, in ordinary circumstances, takes its rise from an 
organ, which in many other species serves the purpose of 
an ovarium, and was termed by Ellis a Vesicle. In this 
manner we can conceive each colony, the individuals of 
which are connected together either mechanically or orga- 
nically, increasing to an indefinite size, and the common 
base acquiring proportional strength by the tubular radicles 
each new branch protrudes. But in what manner are new 
colonies formed ? The specimen examined throws no light 
on this part of the history of the species ; but analogy leads 
to the conclusion, that some of the vesicles may, at times, 
perform their function of ovoviviparous reproduction. The 
appearances exhibited by this coralline lead us to infer, 
that those " little regular arch-like risings," which Ellis 
observed on his specimen of Sertularia myriophyllum, and 
which is common to the species, may be vesicles supporting 
branches similar to our species. 
In the Plumularia hidlata the bodies of the polypi them- 
VOL. v. u 
