the tentacle (his antenna), the ciliated rosette of the first segment, chitinous papillæ, and
fringed scales (simple papillæ), and gives the detailed structure of the feet with figures.
De Saint-Joseph (1888) observed many examples of Halacarus olivaceus on the body of
one. He agrees with me in thinking that S. Idunæ, Rathke, is identical with 8. boa, Johnst.
2. Sthenelais zetlandioa, McIntosh, 1876.
Specific Characters.—Head absent, and body fragmentary. Scales somewhat reni-
form or irregularly rounded, densely covered with low flat papillae, the outer and part of
the posterior edge bearing a closely arranged series of minute clavate cilia. Dorsal lobe
of the foot rather long, and obliquely bevelled from above downward, bearing a tuft of
bristles that are longer and more finely spinous than in 8. boa. Beneath the spine are
a series of small papillae with truncated and papillose extremities. Ventral lobe irregularly
conical, with numerous papillae, at the tip of which are the secondary processes or
warts. Along the ventral border is a series of globose warts. The upper ventral
bristles have proportionally strong shafts, with four or five rows of spines at the distal
end, and a terminal bifid appendage usually of two joints. The slender inferior ventral
have three divisions in the terminal appendage—all with a hooked tip, and a secondary
process beneath.
Habitat.—Dredged off the Shetland Islands by Dr. G-wyn Jeffreys in 1867. Mr.
Harvey-Gribson found a fragment (?) off Port Erin, Isle of Man.
Synonyms.
1876. Sthenelais zetlandica, McIntosh. Trans. Zool. Soc., ix, 390, pi. lxx, f. 15—17.
1886. „ „ Harvey-Gribson. Verm. Liver., p. 151.
1891. ,, Hornell. Op. cit., p. 238.
Head.—Absent in the preparation, and the anterior end injured. The proboscis
appears to have the ordinary structure—with the horny teeth, and the dorsal and ventral
rows of conical papillse.
Body.—About the size of Sthenelais limicola, and having a similar appearance.
The scales are somewhat reniform, or irregularly rounded anteriorly, and the entire
surface densely covered with flat papillae, which on the folded edge of the scale form
low, smooth warts, larger in proportion than in Sthenelais boa. The outer and part of
the posterior edge again bear a somewhat closely arranged series of minute clavate cilia
(Plate XLI, fig. 24), almost globular at the commencement on the posterior border, and
with minute processes or palpocils on the summit, those on the outer edge being more
slender than those on the posterior border.
The feet (Plate XXX, fig. 14) have dorsally a branchial process and three ciliated
T-shaped organs beneath. The superior lobe is rather long, and obliquely bevelled
from above downward. It bears beneath the spine a series of rather small papillae,
which have truncated extremities provided with several accessory papillae. The
superior bristles are longer in proportion than in 8. boa, but do not form so broad a fan
when viewed laterally. They taper to a delicate extremity, and their rows of spines are
distinctly marked, though somewhat finer than in 8. boa. The inferior lobe is irregularly
conical, and has numerous papillæ, the largest near the spine, and just above the
inferior group of bristles. Moreover below the latter is a cluster of smaller papillæ furnished
with the secondary processes or warts at the tip. After a brief interval, a series of
globular warts occurs along the ventral border of the foot. The superior ventral bristles
(Plate XLI, fig. 25, in calcium chloride, and with the basal part of the terminal
appendage slightly folded) have comparatively strong shafts, with four or five rows of
spines at the dilated distal extremity, visible, however, only at its edge. The terminal
appendage as a rule consists of only two divisions, occasionally a more slender form at
the upper border having three. In those with two the terminal portion is only one
fifth the length of the basal. The claw at the tip is distinct and much curved, and the
secondary process projects at a slight angle, the point often touching the tip of the claw.
The basal joint is finely striated, as is likewise the dilated end of the shaft. As we
proceed downwards these bristles become less robust, and the shaft has a more distinct
dorsal curvature, but the terminal region of two divisions remains. Each of the more
slender ventral groups, again, has three divisions in the terminal appendage (Plate XLI,
fig. 26, which represents one of the larger forms© The bristles throughout are tinted
of a light brownish hue.
The ventral cirrus is subulate, and it reaches nearly as far as the fleshy part of the
foot (in spirit). The terminal region, which is elongate-ovoid, is marked from the
succeeding by a distinct shoulder, as if articulated.
The absence of the head makes the generic relations of this species doubtful, but in
the meantime it may be placed under Sthenelais until a more complete example is
obtained. It is one of the many rare forms which the persevering explorations of
Dr. Gwyn Jeffreys in the Zetlandic seas brought within our knowledge.
The 8. fuliginosa of Claparède1 is an allied form, and the 8. minor of Pruvot and
Racovitza2 also approaches this species in regard to the structure of the papillæ and
the general character of the bristles, but differs in the presence of papillæ along the
ventral edge of the foot, and it has fewer papillæ on the scales than in the British form.
3. Sthenelais atlantioa, McIntosh, 1876.
Specific Characters.—Head somewhat ovoid. Median tentacle subulate, and with
a terminal joint. A pair of eyes close together on each side, near the base of the
tentacle. Palpi long, smooth, and tapering. Tentacular cirri show a terminal differentiation,
as in the median tentacle. Body as in 8. zetlandica. Scales thin, rounded or
ovoid in front, reniform throughout the rest of the fragment, covered with sparsely
distributed but clavate cilia, and having a fringe of short clavate cilia, which are only
absent from a portion of the inner and adjoining anterior margin. They are longer and
more numerous than in 8. zetlandica. Dorsal lobe of the feet bevelled from above
1 ‘ Ann. Chet. Naples/ p. 94, pi. iv, f . 2.
3 ‘ Archives Zool. expér./ 1895, p. 465.