Savigny in his ‘ Système ’ 1 made the Aphroditidæ the first family of his Néréidëes,
characterised by having the branchiæ in the form of a ridge or papilla situated superiorly
at the base of the dorsal branch of the foot. They are absent from the second, fourth,
fifth, seventh, ninth, and eleventh pairs of feet, and so on until the twenty-third or
twenty-fifth. They determine by their absence that of the superior cirrus, and are
replaced by scales. The scales, when present, number from, twelve, pairs or fewer to
thirteen pairs or more, and extend to the twenty-third or twenty-fifth segments, and
are followed or not by supernumerary pairs. They are formed of separate membranous
lamellæ, the upper thickened, sometimes horny, the inferior delicate, and attached by a
hollow pedicle to the base of the feet without branchiæ—in a position, however, corresponding
to the attachment of the latter. The mouth has a proboscis and four jaws.
The former is cylindrical, massive, striated transversely, and furnished with a fringe of
small tentacles at the orifice. The jaws are horny or cartilaginous, flat, short, more or
less free at the point, and have a vertical motion on ea.ch other. The eyes are four in
number, two anterior and two posterior. The antennæ are retractile, elongated,
generally complete ; the median of two articulations, the first being short ; the unpaired
the same ; the anterior always present and much larger than the others, finely ringed,
conical, and with tapered tips. The feet have either two divisions or these are united—
furnished with aciculi. Cirri prominent, generally composed of two chief divisions ; the
first, short and thick,'lies at the base of the other, which is retractile. The superior cirri
are large, extending beyond the bristles, while the latter pass beyond the inferior cirri.
The first pair of feet have the divisions intimately united, without bristles or with
numerous bristles, and the two cirri elongated like tentacles. The second pair of feet
have also a long inferior cirrus, a little larger than the succeeding. The intestine is
provided with numerous cæca, which are most distinct in“A.phrodita proper. Savigny,
from the foregoing, used the term (Aphroditidæ) in its widest sense.
In Cuvier’s * Règne Animal ’3 (Mem. Edit.) M. Audouin arranged the Aphroditidæ
and Polynoidæ under the order Dorsibranchiata (corresponding to the Néréidées of
Savigny).
Audouin and Milne Edwards (1834) classed the Aphrodisiens (which included
Aphrodita, Polynoë, Sigalion, and Palmyra) as the first family of their Annélides
Errantes, and they gave a description which defined the somewhat extensive group.
One important feature is the presence of a double row of membranous scales, the elytra
of Savigny, fixed on the dorsum by a pedicle to the superior division of the foot, and according
to the authors filled with ova at certain periods. They occur in some on
all the feet or on alternate feet, while in others they are absent. They refer to small
processes attached to the under surface of the'scales as branchiæ. Cirri, occur on the
segments devoid of elytra, with the exception of Sigalion, where they are present on all
the segments. The feet are bilobed, each division being, armed with a spine, bristles, and
cirri, the last existing on every foot ventrally. In. the first segment the dorsal cirri
become tentacular cirri. The antennæ are attached to the head, and ate three in number
1 * Système des Annélides,’.tome i, 3e part., 1820.
2 MM. Audouin, &c., ‘Règne A n./ 1836—7.
—a median and two lateral. The eyes are usually four in number and placed in pairs—
one in front of the other.
As the result of their own researches they restored the older name Aphrodisiens for
Savigny’s Halith^es, and made three principal groups : (1) those in which the elytra
alternate with dorsal cirri and branchiae, (2) those having these organs on the same foot,
and (3) those devoid of elytra. In the first tribe the authors placed Aphrodita, Polynoe,
and Polyodonta. In the second division, which from the elongated body they termed
Aphrodisiens vermiformes, they ranged Aco&te and Sigalion; while in the third group is
placed Palmyre. We shall deal at present only with the first mentioned, viz. Aphrodita,
which was characterised by the authors as furnished with thirty elytra fixed to feet
which bear neither branchiae nor superior cirri, and which alternate regularly (with the
exception of the fourth and fifth segments) to the twenty-fifth segment, with other feet
which have cirri and branchiae. The elytra fixed to the succeeding segments are differently
arranged. Three antennae are present. The jaws are small and cartilaginous or
absent.
A sea-mouse and parts of its digestive system are figured in Tav. iv, fig. 10, of Delle
Chiaje’s Memoire (1822), but no description is given.
The same author1 (1841) speaks of a pair of oval ovaries in Polyodontes maxillosa,
filled with a transparent liquid at the dissepiments and at the bases of the feet, and of an
analogous group of rosy ovaries in Hermione hystrix, and yellowish ovaries in A. aculeata.
These Meckel considered to be small branchiae. In April they had advanced considerably.
He did not consider the scales respiratory, as Cuvier, Carus, and Duvernoy had
done, and he supported his opinion by the presence of special branchiae in Sigalion
squamosum. He described the ventral ganglionic chain as a nerve-artery in A. aculeata
and H. hystrix, but had seen vascular trunks in both on the intestine. The blood-vessel
in his figure seems to ensheath the oesophageal.trunks and ventral chain. Long before,1 2
he had compared the alimentary system of the Aphroditaceans with that in such as
Pleurophyllidia.
Oersted3 (1843) signalised the Aphroditacea amongst the Nematode-like Chsetopods
as having imperfect branchiae (simple). He considered the scales the branchial organs.
Grube’s description of the Aphroditea in his ‘ Eamilien der Anneliden ’ (1851) is
brief but characteristic. He included Palmyra under the same family.
Sir J. Dalyell4 says that, “ though seemingly timid, the Aphrodita is probably fierce
and rapacious, overpowering creatures incapable of resistance; and there is even reason
to believe that it occasionally devours its own kind.” By Aphrodita he means the
Aphroditacea.
Kinberg6 (1857-8), following on the lines of Audouin and Milne Edwards, grouped
the Aphroditea of Savigny into seven families, the first of which, Aphroditacea, corresponds
with our Aphroditidge. ’ These have an oblong wide body, with a rounded head
1 ‘ Memoire,’ vol. i, p. 121'.
2 1823.
3 ‘ Ann. Danie. Consp.,’ 1843, p. 4.
4 ‘ Powers of the Creator,’ vol. ii, p. 163, 1853.
5 ‘ Eugenics Resa,’ &c., p. 1, 1857-8.