aspect (Pig. 17), the cseoa forming .voluminous organs in the body of the Annelid.
Pallas found nothing in the proboscis (his ventrioulus), whereas in the gut he met with
particles of fuci. In many at St. Andrews and elsewhere mud of various degrees of
darkness occurs in the canal and its branches. Swammerdam thought the ramifications
of the intestine anastomosed with each other.
Scales. The overlapping, irregularly rounded scales1 number fifteen pairs, and are of
considerable size. The first two show a narrow external margin beyond the pedicle, but
in the rest the latter occurs at the external border, and it is proportionally large
throughout, the scale being thus firmly adherent over an extensive surface while readily
moved by the muscles of the parts. The surface of the cuticle on the dorsum and the
scale-pedicle is minutely papillose, but the scale proper is smooth, only a few minute
papillae occurring along the edge. They are often coated witlf patches of a blackish-
brown granular deposit. The size of the scales does not always seem to correspond proportionally
with that of the specimen. Many of the older authors, like .Swammerdam,
considered these organs the gills.
Dorsal Fimbriated Papilla—On the dorsum of the sixth foot an elevated ridge at the
posterior border, rather beyond the line of the scale-pedicles, gives Origin to a short
process with a thin, flat, fimbriated extremity, generally of three divisions. The terminal
fimbrim of the papillae become more complex and the process longer as we._proceed
backwards, the organs appearing, after the sixth, on the eighth, tenth, and every
alternate foot (devoid of scales) to the twenty-sixth, when they occur on th é ' twenty-
seventh and the last, a small one on the twenty-ninth, that-is on the foot behind the last
scale. These organs have been interpreted as branchiae by Pallas, Savigny, Kinberg,
and others; while many, such as Cuvier, Carus, Duvernoy, and Oersted, held that the
scales were respiratory organs.. The great thickness of the cuticle of these processes, and
the absence of large blood-vessels, as De Quatrefages showed, do not favour the view that
they are special branchial structures, though the lobes of the alimentary cseca come dose
to them. The cuticle occasionally may be comparatively thick on the surface of
branchiae, as in certain Euphrosynidae, but it does not attain the great density seen in
these processes of the sea-mouse.
Feet. The structure of the foot is shown in Plate XXXVI, fig. 10 (representing the
tenth foot), and the organ in the various regions of the body conforms to the same pattern.
The dorsal division bears the beautiful iridescent hairs, which gleam with all the beauty
of a permanent rainbow. A dense and most gorgeous tuft of these, thicker than the
dorsal series, occurs just above the ventral division of the foot, and extends more or less
to the dorsal edge of the spines, where another dense tuft of hairs, less brilliant than the
first series and much finer, occurs, and which form the felt on the dorsum. This property
of felting does not appear to be due to any roughness of the exterior of these fine hairs, :
though fracture may render such rough, but to their flexible and attenuated condition*
The tips of the hairs are often curved (see Plate XXXV, fig. 27). The first-mentioned
series are brittle and gorgeously iridescent, the tips under a lens being wavy, a feature
1 Darwin was of opinion that these were homologous with the wings and elytra of insects, “ and
it is not improbable that with our existing insects, organs which at an ancient period served for
respiration have actually been converted into organs of flight.” Unfortunately, proof is deficient.
due not to any change in outline, but to the play of light on the organs. The rainbow
lustre is lost on drying these hairs in a spirit-preparation, but is again restored on
immersion in water. De Saint-Joseph (1888)< thinks Kriikenberg1 was wrong in considering
the felt was like chitin; it is more like keratin.
The lustrous brown spines spring in a fan-shaped series from the middle of the
foot, and form slightly curved sharp weapons of defence. They end in an acute two-
edged tip, and readily pierce the skin. They have the same brittle chitinous structure
as the other spines in this species.
In young specimens the dorsal spines are longer, more tapered and curved, and
meet in the middle of the dorsum so as to guard the back, as in other Aphroditidse.
These and the rest of the spines are also often of a lighter golden hue. The thin and
comparatively even coating of felt which covers the dorsum of some young specimens
gives a character to such examples on clean ground, as off the west sands at St.
Andrews. A great change ensues in these bristles during growth. Small specimens
from a quarter of an inch upward to an inch appear to be common on muddy ground,
and are densely coated with it,-—as, for instance, in St. Magnus Bay, between the
Skerries and Fetlar, and the Fjords of Norway (Canon Norman). On sandy ground, on
the other hand, they are beautifully clean, and the long golden spines curve as guards
over the dorsum.
The first foot bears a dense tuft of simple, slightly iridescent, slender, hair-like
bristles, chiefly directed upwards and forwards. In the middle is another fan-shaped
series directed forward and slightly curved (convexity outward). Below is a third
group of similar structure, probably representing the ventral series, directed downwards
and forwards, and with their convexity (for they are stiffish) downwards. On the outer
side of the bases of the first two series are the tentacular cirri. This foot shows no
marked division into dorsal and ventral parts, but has a somewhat clavate outline.
The second foot has the ventral division separated. Dorsally the rounded boss has
externally a dense series of stiff hairs, which stand out in a fan-shaped manner, while
towards the dorsal median line (Plate XXXV, fig. 25) the second or adjoining series are
modified to form the very slender hairs of which the felt is composed. The ventral
division bears smooth spines (Plate XXXVI, fig. 18), and inferiorly the tuft of somewhat
stiff, pinnate bristles (Plate XXVI, fig. 17).
The ventral division of each typical foot, as noticed by Baster and Swammerdam,
bears three series of bristles arranged in transverse rows (Plate XXXVI, figs. 10 and 22).
The strongest occur dorsally, and consist of about three powerful dark brown bristles
(Plate XXXVI, fig. 2 c), flattened at the tip, which varies in condition, though funda-
mentallv the type is somewhat hastate, as observed in the posterior region of the body
(Plate XXXVI, tig. 20). In front view (a) the tip resembles a broad spear, sometimes
asymmetrical; in lateral view, again, the tip (6) is more or less tapered, and posteriorly
has a slight dilatation at the commencement of the shaft.
The middle series (Plate XXXV, fig. 25 6) has the same type, but the bristles are
paler and more numerous, about eight occurring in the row. The curvature at the tip is
more distinct. Posteriorly the hastate condition is evident (Plate XXXVI, fig. 19).
1 ‘ Vergleichende physiol. -Stud./ 2e ser., part 1, p. 54, Heidelberg, 1882, 8vo.