134 
CLASS II.— ORDER II. 
nearly equal. The substance of the part connect* 
ing the articulations in these Polypidoms possesses 
a rigidity and fragility, somewhat resembling the Isis 
when divested of its polypiferous rind. 
The Amphiroas multiply by tubercular ovaria, 
placed on the cretaceous part of the articulations ; 
these ovaria are sometimes abundant, and sometimes 
scanty ; they appear organised like the pyriform ovaria 
of the Corallinas and Janias. 
The Amphiroas differ in their forms more than the 
Corallinas ; in the latter the articulations are nearly 
alike : but in the former they are sometimes found 
cylindrical in the stem, compressed in the branches, 
and either flat or spoon-shaped at the extremities. 
They vary equally in their ramifications ; dispersed 
in some, dichotomous in a few, and in others ver- 
ticillated once or many times, the verticils in many 
species consisting of numerous branches; some- 
times all these characters are found united in the 
same individual. 
Their colours are similar to those of the Corallinas. 
They do not exceed a decimetre in height, nor are 
they ever less than three or four centimetres. 
They are usually found in warm and temperate 
latitudes. I am inclined to think they are not inha- 
bitants of the colder regions. They are attached to 
rocks and other hard substances, never parasites on 
marine plants. 
The Corallina Officinalis, or Corsican moss, is some- 
times chiefly composed of polypidoms of this genus. 
