226 
POPULAR SCIENCE REVIEW. 
various species many quaint and elegant forms, hyaline or 
amber- tinted, and often adorned with curiously crenated or 
spinous margins. In one section the calycles are set close 
together in a continuous series (PI. CX., fig. 1); in another 
they are more or less remote (PL CXI., fig. 1) ; and this ap- 
parently trivial distinction is associated with other more im- 
portant differences which divide the family into two well- 
marked groups. Of these I shall have more to say hereafter. 
A dry account of the structural features and the arrange- 
ment of parts, however accurate, can give no idea of the living 
beauty of these exquisite organisms. The grace of their curves, 
the hyaline delicacy of their texture, the nameless charm of 
their entire figure cannot be expressed in a diagnosis. In the 
attempt to render them the pencil is at fault — much more the 
pen. Yet I must endeavour to give a general notion of a 
characteristic form in the living state, and to suggest the prin- 
cipal elements of the beauty that is common to the entire 
family before proceeding to the special points of structure to 
which this paper will be chiefly devoted. 
I shall select as an illustration one of the smaller British 
species (PI. CXI., fig. 2), which is neither better nor worse than 
its kindred, but a fair average specimen of its race. Imagine, 
then, a piece of rock, the surface of which and of the sinuous 
tubes of the Seiyula incrusting it, is netted over by the finest 
of fibres, from which rises a whole forest of exquisite plumes. 
The tallest of them is less than an inch in height ; they are all 
but colourless, so delicate is the horny material composing them, 
and their slender, shadowy forms are only distinguishable in a 
strong light. The trailing tubular thread from which they 
spring may remind us of the rhizome that gives origin to the 
fronds of the fern ; it is the common base of the Plumularian 
commonwealth, holding its many families in organic union, and 
binding them to the surface over which they spread. Each 
plume * was pushed forth as a bud from the prolific pulp per- 
vading it, and is itself a branching tube inclosing an offset from 
the common flesh. 
The plume is a colony, sharing the life of a great common- 
wealth and helping to nourish and enlarge it. The delicate 
pinnae, set for the most part alternately along its main stem, 
bear at intervals minute transparent cups (PI. CXI., fig. 3 c), 
the homes of as many hydrse which expand above them their 
wreaths of slender, beaded arms, all of them bound together as 
one organism by the ramified thread of flesh pervading the struc- 
ture. In this section of the Plumularian family, the polypites 
are not wholly retractile within the calycle ; only the base of 
* Except the first, which is developed immediately from the embryo. 
