PENNATULIDA. 243 
gonia, throws some curious light on the habits of. these creatures. 
“This zoophyte consists of a thin, straight, fleshy stem, with alternate 
rows of polypi on each side, and surrounding. an elastic stony axis, 
varying in length: from, eight: inches. to: two,;feet.: The stem at one 
extremity is'truncaté, but:at. the‘other is terminated, by a vermiform 
fleshy appendage. The stony axis, which gives strength to the stem, 
may be tracéd at the extremity into-a mere vessel filled with granular 
matter. At low. water, hundreds:of these.zoophytes might be. seen 
projecting like stubble, with: the’ truncate end, upwards, a few inches 
above the surface of the muddy sand. When touched or pulled, 
they suddenly drew themseves in with force, so as nearly, or quite, to 
disappear. By this action, the highly elastic axis must be bent at the 
lower extremity, where it-is naturally slightly curved ; and I imagine 
it is‘by this elasticity alone that the.zoephyte is enabled to rise again 
through the mud, Each polyp, though closely united to its brethren, 
has a-distinct: mouth, body, and tentacula. Of these polyps, in a 
large Specimen there; must be: many: thousands, yet we see that they 
act by one movement. ' They-have ‘also ‘one central axis connected 
with a system of obscure circulation, and the ova are produced in an 
organ distinct from the separate individuals. For,” adds-Mr. Darwin,, 
in a note, “ the cavities leading from the fleshy compartments of the 
extremity were filled: with a yellow pulpy matter which, under a 
microscope, consisted of rounded semi-transparent grains aggregated 
together into particles of various sizes. All such particles, as well as 
separate: grains, possessed the power of rapid motion, generally 
revolving round different axes, but sometimes progressive.” 
Virgularia mirabilis is common in the east and north coasts of 
Scotland ; it is found in the North Sea, and as far north as Norway. 
In Zetland it:is known as the sea-rush.. It is abundant in Belfast 
Lough, but, from its brittle nature, perfect specimens are difficult to 
obtain. ~~ CAM on 
The genus Virgularia differs from that of Pennatula chiefly in the 
development, of the axis of the colony and_ the shortness of the 
pinne, which carry the polyps ; and also in this, that no spicula enter 
into the composition of its: softer, parts.. 
“ V, mirabilis seems,” says Sowerby, “ to represent a quill stripped 
of its feathers. The base looks like a pen in this as in other species, 
swelling a little way from the end, and then tapering. The upper 
part is thicker, with alternate .semicircular pectinated’ swellings, 
larger towards the middle, tapering upwards, and terminating in a 
thin bony substance, which passes through the whole extent, and is 
from six to ten inches in length.” 
Q2 
