Fam. 3, Plate 43.
Genus 10. ANTIOPA,* Alder and Hancock.
Corpus ovato-oblongum, postice acuminatum. Caput subinferius, velo parvo obtectum. Maxilla
corneae. Tentacula 4, quorum 2 majora, dorsalia, et 2 minora labialia. Tentacula dorsalia laminata.
basibus cristae arcuatae centrali conjunctis. Branchia papillosae, ovatae, utrinque ad marginem lateralem
et prominentem dorsi dispositae, et anterius circum caput collocatae. Anus posticus, in line«! mediä
dorsi situs. Apertura genitalis ad latus dextrum.
The principal character which induces us to consider this genus distinct from Proctonotus
is the remarkable crest between the dorsal tentacles, a character so peculiar as apparently to
warrant a generic distinction. The lamellated form of the tentacles, and the length and bifid
termination of the glands of the papillae, may possibly prove to be of generic importance; but
from our present imperfect knowledge of these animals, confined in each genus to a single
species, and in Proctonotus to a single perfect specimen, we can scarcely determine the value
of these characters, nor the extent of their variation, with any degree of certainty. The
genus was first described by M. Verany of Genoa, in the ‘Revue Cuvierienne,’ for 1844,
under the name of Janus, a name previously appropriated by Mr. Stevens to a genus of
Hymenopterous insects in 1835. At the time when we proposed for it the generic appellation
here adopted,! we had not the means of ascertaining its identity with the Janus of M. Verany,
which we have since had ample opportunity of doing through the kindness of that
distinguished naturalist; but, adopting the views expressed in the rules for zoological
nomenclature, published by the British Association, as to the propriety of discarding duplicate
names, we have retained the name of Antiopa in preference to that of Janus, which, under
other circumstances, would have been entitled to priority.
The body in this genus is ovate, rather depressed, and tapering to a point posteriorly.
It has a produced ridge on each side assuming the appearance of a rudimentary cloak. The
dorsal tentacles are laminated, non-retractile, and united at the base, and for a short way up,
to an arched fleshy crest. The head is inferior, subangular in form, and without a veil, but
having the margin of the lips projecting considerably, with two small linear or cylindrical
oral tentacles. The mouth is provided with strong homy jaws, and a broadish denticulated
tongue. The branchiae are papillose and elongated, arranged round the head and down each
side of the back, nearly meeting behind. At their posterior termination, a median ridge runs
down to the tail. The anus is situated posteriorly on the median line of the back, a little in
advance of the termination of the branchiae. It is tubular and conspicuous. The foot is
* A classical proper name.
t Ann. Nat. Hist., 2d series, v. 1, p. 190.