Cams in the ‘ Prodromus Faunas Mediterraneas’ gives the following:—Head with
median antenna and generally two short lobulated or fleshy-membranous organs at the
base; maxillae well developed; feet all furnished with branchiae, and the anterior pair
turned to the front, so that the cirri and setae form part of the cephalic apparatus ; body
elongate, vermiform.
Pruvot and Racovitza1 have recently drawn attention to the homologies of the head-
processes in Sthenelais, and express the view that the subulate cirrus which springs from
the inner side of the bristle-tuft of the first foot (bearing the tentacular cirri) is the lateral
tentacle (their lateral antenna). In their descriptions they further point out the exact
arrangement of the dorsal and the ventral bristles, the latter forming a horseshoe with
the opening in front, and with a spur dorsally and ventrally, each of the latter being
characterised by a change in the structure of the bristles.
1. Sthenelais boa, Johnston, 1833. Plate XXVI, figs. 7 and 8.
Specific Characters,—Head crimson, broadly ovate, bounded by a nuchal collar
posteriorly. Median ridge passes in front into the broad basal process (ceratophore) of
the median tentacle, which is short and subulate. Two flap-like organs (ctenidia) occur
at each side, the anterior the longer. Two eyes on each side, the larger anterior pair
almost hidden by the latter processes, and looking forward and outward. The posterior
pair are on the dorsum, a little behind the bases of the processes. A truncated papilla
at each side of the head posteriorly. Head fixed to the massive parts of the first feet,
which bear externally two tapering cirri of considerable length. Behind thé dorsal
tentacle is a T-shaped ciliated process. To the inner side of the ventral cirrus of the
first pair of feet is a sickle-shaped blunt appendage (ctenidium)—richly ciliated, and
probably branchial. A short subulate cirrus (lateral tentacle) exists superiorly on the
inner side of the bristle-tuft. The long, subulate, and smooth palpus springs from this
basal process, which also carries a double series of long, tapering, slender, spinous
bristles. Body elongated, little tapered anteriorly, but gradually diminishing posteriorly.
I t is rounded dorsally and flattened ventrally, greyish or bluish-green, the latter or flesh-
colour characterising the iridescent ventral surface. Segmental eminence at the base of
each foot, and a ciliated funnel-shaped process on the foot. Scales 156 pairs; mostly
reniform, and with numerous minute papillas, while the outer border bears a series of
large simple papillae. A well-developed branchial process exists above each foot, and on
the dorsal ridge beneath it are three T-shaped ciliated organs (ctenidia). The dorsal
bristles are long, somewhat stiff and finely tapered, as well as spinous from a little above
the base to the apex. Upper set of the ventral bristles with simple tips, boldly spinous;
then some with a tapering bifid appendage of about three joints, the end of the shaft
having a few rows of spines. The main part of the division, forming the large
curve of the horseshoe, has stout bristles with bevelled ends to the shafts, and a short
beaked appendage of one segment. Inferiorly the lower spur of the horseshoe has
1 | Archives Zoolog. expér.,’ p. 452, 3® Sér., iii, 1895.
more slender, forms, with a few rows of spines on the slightly expanded distal regions of
the shafts, and an appendage of one, to four joints. A group of long papillas occurs at
the anterior edge of the superior division, one above the spine of the ventral division,
and a ciliated or papillose frill is found at the base of the lowest slender bristles. Ventral
cirrus elongate, subulate, barely reaching the tip of the fleshy part of the foot.
S ynonyms.
1833.
1839.
1843.
1851.
1861.
1865.
1867.
1873.
1875.
1876.
1879.
1880.
1883.
1884.
1888.
1890.
1891.
Sigalion boa, Johnston. Loud. Mag. Nat. Hist., vi, 322, f. 42.
,, „ idem. Ann. Nat. Hist., ii, 439, pi. xxiii, f. 6—15.
„ Idunæ, H. Rathke. Nova Act. Acad. Caesar. Nat. Cur., xx, 150, Tab. ix, f. j —8.
„ ' - ,, Grube. Fam. Annel., p. 38.
,, bod, Williams. Kept. Brit. Assoc., 1851, p. 201.
„ Idunæ, Sars. Nyt. Mag. Natur., xi, 3, p. 254. •
„ > „ idem. Vid. Selsk. Fork., 1861, p. 1 (sep. copy).
,, ,, Malmgren. Nord. Hafs.-Ann., p. 86.
Sthenelais Idunæ and S. boa, De Quatrefages. Ann., i, p. 276.
Sigalion boa, Johnston. Cat. Brit. Mus., 124, pi. 13, f. 6.
„ ,, Parfitt. Annel. Devon., p. 19.
Sthenelais Idunæ, Sars. Bid. Christ. Faun., p. 14.
Sigalion Idunæ, Willeïnoes-Suhm. Zeit, f. w. Zool., xxii, p. 347.
,, ,, Ehlers. Annel. ‘Porcupine,’ 1869, op. dit., p. 18.
Sthenelais boa, McIntosh. Trans. Zool. Soc., ix, p. 390.
Sigalion Idunæ, Tauber. Ann. Danic., 83.
Sthenelais Idunæ, Langerhans. Zeit. f. w. Zool., xxxiii, p. 276, Taf. xiv, f. 6.
Sigalion Idunæ, Levinsen. Nord. Annul., 199.
,, ,, V. Carus. Faun. Médit., p. 205.
Sthenelais Idunæ, De St.-Joseph. Ann. d. Sc. Nat. (7), v, p. 187, pl. viii, f. 55.
Sigalion Idunæ, Malaquin. Ann. Boulon., p. 23.
„ boa, Hornell. Op. cit., p. 238.
Ha&itfatfE-Ranges from Shetland to the Channel Islands, being procured by the
dredge in the former and between tide-marks in the latter. I t appears to be a generally
distributed species, frequenting both shores of Ireland, and extending to Norway and
Sweden. Ehlers gives a depth of 60 to 80 fathoms in the Minch during the ‘ Porcupine ’
Expedition of 1869. Shores of France.
Read (Plate XXIX, fig. 1) of a fine crimson hue, somewhat broadly ovate, and
separated from the body by a nuchal collar. Anteriorly a median ridge terminates in
the broad basal process for the pale median tentacle, which is comparatively short. At
the sides of .the basal process (ceratophore) are a pair of flap-like organs (ctenidia), the
anterior being the longer, the posterior the shorter. Both-are rather flattened, and move
freely with the broad tentacular base (first foot) on the head—which is fixed. At their
base externally on each side are the eyes, the anterior and larger pair of which are almost
hidden under these processes—when viewed from the dorsum, especially as they are also
placed on the front of the head so as to look forward and outward. The posterior pair
lie a little behind their bases on the dorsum. At the posterior border on each side is a
well-marked process or papilla with a truncated tip (one of the “ organes nucaux”). The