1912. Pista cristata, Gravier. 2nd Exped. Antarot. Fr., p. 133.
„ „ Meyer, A. H. Inaag. Dissert; Kiel, p. 36.
1914. ,, „ Southern. Proc. Roy. Irish Acad.,'vol. xxxi, No. 47, p. 123.
„ „ ,, Fauvel. Campag. Scient. Monaco, xlvi, p. 302.
1915. „ „ McIntosh. Ann. Nat. Hist., ser. 8,.vol. xv, p. 20.
1917. ,, „ Hessle. Zool. Bidr. Uppsala, v, p. 154.
Habitat.—Dredged in 4—5 fathoms in Ardmaddy Bay, Lochmaddy, amongst shelly
mud and grey clay (W. C. M.). Dredged in St. Magnus Bay, Shetland, in 80 fathoms;
50 miles west of Valentia in 160 fathoms; Outer Haaf, Skerries, Shetland, in 70—80
fathoms (J. G. J.); usually in deep water; Plymouth (Spence Bate and B. Rowe);
Berehaven, Ireland, and S.W. Ireland, R. I. Acad. Exped., 1885; Blacksod and other
bays on west coast, Ireland (Southern).
Abroad it occurs off Sweden, Norway and Finmark (Malmgren); Canada (dredged
by Whiteaves) ; Mediterranean (Grube, Marion, Marenzeller, Lo Bianco) ; North America
and Congo var. ? (Grube); New England and Atlantic coast, U.S.A. (Verrill); Magellan
(Ehlers); Antarctic Seas (Gravier); amongst Posidonia, Isle of St. Marguerite, Cannes,
and at St. Raphael amongst Zostera (De St. Joseph); Virginia coast (Webster); Siberia
and Behring’s Sea (Wiren); White Sea (Ssolowiew).
The cephalic plate has a thick dorsal collar and the margin passes externaffy and
ventrally to join the anterior fold, though it does not run evenly into it, a notch or a fold
separating it from the raised anterior fold, which sometimes has a median projection with
symmetrical lateral curves or in others slight frills. This anterior or supra-oral fold
does not project so far forward as in many Terebellids, and it sometimes shows an inner
fold over the mouth. The pale orange tentacles seem to be of moderate length and
grooved, but are somewhat more slender and tapered than in ordinary Terebellids.
Below the mouth is a well-developed tongue-like process which pushes the rim of the
first segment backward when it projects, and ventrally it has a narrow rim.
The body is comparatively short and in the preparations is less dilated anteriorly
than in the ordinary Terebellid. It tapers posteriorly to a slender tail with a terminal
anus, which has four large rounded papillae, two dorsal and two, slightly more prominent,
ventral. Dorsally the body is rounded, ventrally flattened at the shields in front, and
then grooved throughout the rest of its extent. Anteriorly behind the dorsal collar the
setigerous papillae approach the median line, where a bifid process occurs in front of
them, and from the sides of the divisions the branchial stem originates— not always in the
same place, for in some the right branchia springs antero-laterally in regard to the right
process, whilst the left branchia arises behind and to the left of the left process. The
free margin of the first segment forms a continuous fold ventrally which ends dorso-
laterally in a rounded free flap, and a process is continued dorsally beneath its edge to
the representatives of the setigerous process, which lies immediately behind the bifid cone
formerly mentioned. The next segment has ventrally a large free lateral flap on each
side whilst the median is differentiated into a narrow scute. The following segment has
a still larger lateral flap which stretches further outward and upward and almost touches
the base of the branchial stalk in the preparation. It thins off toward the narrow scute
in the mid-ventral line. Laterally it ensheaths the lamella in front of it.
The ventral scutes are about seventeen in number. Vesicles four or five small
terminal median scutes, and after them a median groove with a raised line continuous to
the posterior end. Behind and above the third and fourth bristle-tufts a smoothly rounded
process or long papilla occurs, and in some two are found behind the fourth. In the
Irish examples they are clavate. Occasionally a smaller papilla appears behind the fifth.
In the Hebridean forms the tentacles are pale orange, the body of a uniform reddish
orange with a deep orange bar at each scute inferiorly. The lips are reddish, and a deep
red patch occurs at the anterior part of the second region. The posterior part of the
body is pale orange. De St. Joseph states the colour is greyish rose with pale tentacles.
The branchia on each side arises by a long trunk in the line of the second large
lateral flap (third segment) and quite on the dorsum. The distal region is finely
branched, the whole forming a whorled arbuscle so characteristic of the genus.
Occasionally a third and smaller stem springs from the segment in front, and its
branches have the same arrangement. , In an example from Shetland two large
branchige of different sizes arose from the second segment, and two smaller, also of
different sizes, arose from the third. In some the whorled condition is conspicuous,
tier after tier leading to the somewhat truncate tip. It is noteworthy that the branchige
cling to segments 2 and 3.
The next segment (fourth) bears a setigerous process and a ridge but no hooks.
As indicated, the anterior setigerous processes are dorsal in position, but they soon
become lateral. Sixteen are present. Those in front and rear are less prominent
than the intermediate processes. The pale golden longer bristles have nearly cylindrical
shafts, the proximal ends being narrowed only for a short distance, and they are finely
striated, whilst the distal ends are curved, tapered, and soon end in a fine point, the
sides of the tip having well-marked wings. The tip is curved and directed dorsally
and posteriorly—that is, the convexity is in front. The shorter bristles have little more
than the tips projecting uniformly beyond the surface of the skin, and they show the
same form and curvature of the tip.
The hooks commence opposite the second setigerous process—that is, the fifth
segment—as a single row, and the ridges leave a considerable interval between them
and the scutes. The rows remain uniserial till the ninth or tenth when a biserial
arrangement occurs to the. twentieth. The hooks (Plate CXXIV, fig. 9) have a rather
short, stout main fang with three or four teeth above it in lateral view, and oblique
striae pass from these to the posterior outline of the neck. The outline below the main
fang is slightly angular and wide, whilst the median process on the anterior outline
forms a short cone with a broad base, the line then trending at a different angle
downward. The posterior outline is nearly straight (very slightly convex); then it
bends outward at the point of attachment of the ligament, which passes off above the
lower margin of the base, and thus the appearance of the hook is diagnostic. The basal
region is comparatively deep and has a process at its anterior and inferior angle. The
long ridges for the hooks cease with the bristles, and thereafter uncinigerous processes
project from the posterior border of each segment, the glandular tissue forming a belt
between them. Posteriorly the processes bear a single row of hooks. In connection
with the development of these bopjcs Jlessle figures one (Plate III, fig. 3) in its capsule,
190