32 
colour. The pinnae are of a lighter colonr, alternate, closely 
arranged in pairs on each inlcrnode, and vary from one eight 
to two thirds of an inch in length. The cells are uniseruj > 
crowded, and enp-sbaped ; the apertures, patulous, deep '} 
notched with about eight indentations, and at a short distan^ 
beneath the rim is a stout rounded spine. Kach cell rests 0 
a separate internode of the pinna. The vesicles, though li a . 
to much variation, have all a very peculiar and characterise 
appearance, resembling minute barrels, embraced with tr° 
five to nine serrated ribs. They are quite transparent w'h e ^ 
living, allowing their irregularly shaped ova to be s ce j 
through the sides; but when dry, they become opaque and 0 
a pearly hue. They are generally attached to the pij n ' 
throughout their length by a dorsal band. This band ^ 
sometimes free and arched, and the vesicles attached on!) 
the extremities. The circular ribs have sometimes only 00 
prominent serrated rim and at others two. c j, 
The description of the cells given above, is taken from s' 1 j 
specimens as most nearly approach to the descriptions 8,1 
figures of authors, more especially of Ellis and Johns*® 
But there are variations from this standard, too remarkably 
be passed unnoticed. In no specimen have I seen the cell* * 
crowded as in Johnston’s figure; Ellis’ at pi. 7, more clos® 
approaches to the mode of distribution observed in Corn'* 
specimens, but he has omitted the sub-marginal spine ^ 
artist having drawn from an oblique back view, instead 0 ^ 
lateral one, as lie himself remarks. In one variety the 
are deeply tubular; the mouth is deeply indented with h () 
six, or seven teeth; the spine beneath the aperture, is 
and in those cells on the lower pinnae, frequently tv *‘ c< y 
long as the diameter of the cell. Above each aperture 3 j 
attached to the upper portion of each internode, is a s11 jj 
tubular process which lies across the mouth of the cel*y 
has a rounded termination, with a subterminal opening 00 
upper surface, very closely resembling what is observe fll 
the Cellaria JSursaria or shepherd’s purse Coralline : a y, 
more clearly observable in the dried than in the living s ' j, 
There is also a minute variety growing on the smaller 
stones and shells about low water mark, which rarely esCt jef 
half an inch in height; in which, the pinnae are very s '» 1 f > r e' 
and long, equalling in length, the height of the stem. J 
sembles the common specimens in every respect, except y 
every part is more minute. Though these are here 
varieties, yet one of them may probably prove a distinct sp l 
The figure of this species, illustrating this essay, i s 0 
natural size of a very fine specimen from deep water. 0 lflP> e 
draughtsman lias omitted the cells on a portion of the P 
on the right side. 
