28 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [322] 
The crooked, round, calcareous tubes made by Serpula dianthus V., 
are often to be found adhering to the under surfaces and sides of stones 
near low-water mark, and also in the pools in more exposed situations ; 
sometimes they are even aggregated together into masses. When dis- 
turbed the worm suddenly withdraws its beautiful wreath of gills into 
its tube and closes the aperture closely by means of a curious plug or 
operculum. This is placed at the end of a rather long pedicle, and is 
funnel-shaped, the outside longitudinally striated and the edge bordered 
by about thirty sharp denticles; from the middle of the upper side 
another smaller, short, funnel-shaped process arises, the edge of which 
is divided into twelve or thirteen, long, rather slender, rigid processes, 
which are usually a little curved inward at the top, but may be spread 
apart in a stellate form. A small, rudimentary, club-shaped operculum 
exists on the other side. When these tubes are placed in sea-water and 
left undisturbed for a short time, the occupant will cautiously push out 
its operculum and display its elegant wreath of branchiz, which varies 
much in color in different specimens, but often recalls the varied hues 
and forms of different kinds of pinks, (Dianthus.) The name which I have 
given to it alludes to this resemblance. Fine specimens of this Serpula 
may often be found, also, in the pools near low-water mark, attached to 
the upper surfaces or sides of rocks, and in such situation they display 
their charms to great advantage. The wreath of branchie is nearly 
circular, consisting of two symmetrical parts, each of which is made up 
of about eighteen pectinate branchie; these are covered on their inner 
surfaces with slender filaments which extend nearly to the ends, but 
leave the tips naked. Young specimens have fewer branchiz. In the 
more common varieties these branchie are purple at base, with narrow 
bands of light red or pale yellowish green; above this they are trans- 
versely banded or annulated with purplish brown, alternating with yel- 
lowish green, or with purple and white; the pinne usually correspond 
in color to the part from which they arise, but are sometimes all purple. 
In other specimens the branchie are yellowish white, or greenish white, 
banded with brown. In one variety (citrina) they are bright lemon- 
yellow, or orange-colored, throughout. The operculum, in all the varie- 
ties, is usually brownish green above, with the sides purplish brown, 
lined with whitish near the edge, and with a greenish white band at the 
base; the pedicle is usually purplish, with two or more bands of white. 
The body is usually deep greenish yellow, with the back lemon-yellow; 
the collar is broad with an undulated border, and is pale green, veined 
with darker green blood-vessels. This species is also often met with in 
dredging on shelly bottoms. 
The Potamilla oculifera (Plate XVII, fig. 86) is another beautiful 
annelid, related somewhat to the Serpula, but its tubes are tough and 
flexible ; they are constructed out of fine sand and other foreign matters, 
glued firmly together with the special secretions of the animal. These 
tubes are often found attached to the under sides of stones, but, passing 
