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ANATÖMT OF G-OITIODOEIS.%1
Fam. 1, Plate 17.
Genus 2. GONIODORIS,* Fokbes.
Corpus limaciforme, subangulatum, postice acuminatum, pallio parvo marginibus reflexis ptene
obtectum. Caput ultra pallium prominens, in tentacula 2 labialia complanata extensum. Tentacula
dorsalia 2, laminata, non retractilia. Branchiae plumosae, non retractiles, postice in lineit mediS, dorsi
anum circumdantes. Apertura genitalis ad latus dextrum.
This genus has been very properly separated from Doris by Professor Edward Forbes,
who described it in the ‘Annals of Natural History,’ for March 1840-t It is distinguished
from Doris by the small cloak, the more angular body, and the tapering form of the posterior
extremity. To these characters we have added the exposure of the head beyond the cloak in
front, and the non-retractibility of the dorsal tentacles and branchial plumes.
The additional characters we consider necessary for the more accurate definition of the
genus, though by thus restricting it, we exclude a beautiful group of the Dorididm, with a small
cloak, peculiar to warmer climates, and distinguished by the brilliancy of their colours, which
are generally disposed in stripes, spots, or marginal bands. In this group, which it was
the original intention of Professor Forbes to include in his genus, the cloak, though small
and narrow, is advanced before the head, and the dorsal tentacles are retractile within
cavities; the body also has a more bi-lamellar form. The group in question appears td us to
constitute a well-marked genus, distinct from Goniodoris, from which we have consequently
excluded it. Goniodoris, as now restricted, contains a very limited number of species,
confined, so far as we at present know, to European seas. Herrmannsen erroneously states
that the type of this genus is the Doris gracilis of Rapp, a Mediterranean species, of deep blue
colour with white stripes, belonging to the southern group already mentioned. The true type
of Goniodoris we take to be the Doris nodosa of Montagu, of which the Goniodoris emargirmta,
described by Professor Forbes in the paper where he characterises the genus, is a variety..
This genus has the body of a sub-quadrilateral form, with elevated sides and tapering
posteriorly to a pointed tail. The cloak is small with a waved margin, generally reflected,
and is truncated or sinuated posteriorly immediately behind the vent. A median ridge,
sometimes not very distinctly marked, on the cloak, is continued conspicuously to the tail.
The head extends beyond the cloak in front, and is covered by a subvelar expansion, which
is produced into flattened oral tentacles at the sides. The mouth is inferior, without corneous
jaws, but with a spinous prehensile collar, and a denticulated tongue. The dorsal tentacles
are clavate and laminated, and are non-retractile. The branchiae are plumose, and surround
* From yoivia, an angle, and Doris. t Vol. 5.