Obs. The differences between this specimen and the types in the
form of tho verrucæ appear to be due to their more expanded condition
at time of death in this than in the type specimens. Unfortunately
no spirit-specimens have as yet reached the Museum.
MEL1TÏÏÆIDÆ.
Alelithæaceæ, Kolliker, leones Histiol. p. 142.
Melithæadæ, Mopselladæ, and Elliselladæ, Gray, Cat. Lithoph. Brit.
Mus. (1870) pp. 3, 6, 24.
The two first-named of Dr. Gray’s families cannot possibly be
maintained distinct from each other, as of the genera which he has
placed iu the first, Alelithcea {Melitodes) includes, as is shown by a
careful study of the spicular characters, Anicella, which he has placed
in the second ; the only distinctive character by which the Aleli-
thæadæ are alleged to he separated from the Alopsellidæ, viz. the
perforation by the longitudinal coenenchymal canals of the lower
joints of the hard axis, is exhibited also by four out of the five
genera which make up the latter family; this may readily be ascertained
by examination of adult specimens representing these genera.
For this reason I have been obliged to relinquish this character in
the separation of the genera, except in the case of Clathraria and
the new genus Psilacabaria, and have in this Eeport reconsidered
the genera and species involved, and after comparing them with the
rich collection already iu the national museum, embracing almost
every known species, arranged them mainly according to spicular
characters, thus following the plan which has been adopted with
such success in other groups of the Alcyonaria by Kolliker and
Yerrill. The Elliselladæ, Gray, include a Melithæid {Wrightella).
The family thus constituted is represented in the present collection
by the proportionally large number of six species, of which
four are new, one appearing to he generically distinct from all other
known forms, and remarkable further for its pure white colour and
slight habit, unexampled in the family. The existence of a dimorphism
of the zooids, long known to obtain in the Pennatulida, and
treated of in the Alcyouiidæ {Heteroxenia, Kolliker ; Sarcophytum,
Aloseley, Eeport etc. ‘Challenger,’ vol. i. p. 118), and by Prof. Aloseley
in the Coralliidæ (Quart. Journ. Micr. Science, n. s. vol. xxii. p. 396),
and stated by Hickson (Quart. Journ. Sci. 1883, Oct., p. 574) to occur
in the Briareidæ {Paragorgia), a fact which I am able to confirm
from specimens in the British Museum, was also pointed out for the
first time in the present family by Mr. Hickson, from information w ith
which I furnished him, viz. in a new species (i¥. albitincta) of the
genus Melitodes. In this species, the only one of between 20 and 30
species of the family in which I have observed it, this phenomenon
occurs in a somewhat remarkable manner, partly owing to which I
had at first overlooked it ; but on my attention being called by the
artist, Mr. Highley, to certain projections on some of the branches,
larger than the ordinary verrucæ, I examined the corallum more
carefully and found that, in the proportion of about 1 to 30 of the
ordinarjj verrucæ, or about one to each internode, some large verrucæ
occurred, about twice the diameter of the usual forms ; this was the
case only on the medium-sized and larger branches. Unfortunately
no spirit-specimens of the species were obtained ; hut the examination
of the open verrucæ shows 8 short spiculate tentacle-lobes,
converging like the segments of an orange, within both the smaller
and larger verrucæ. This is therefore a case of dimorphism much
less strongly marked than and of a different character from th at of
the Pennatulida, and of Corallium aud Sarcophytum, where the
asexual zooids have no tentacles. Possibly, when spirit-specimens
are_ examined, it will be found th a t these two kinds of tentaculate
individuals represent the two kinds of “ polypes” (viz. rudimentary
sexual and perfect asexual) which occur in Halisceptrum (Kolliker,
‘ Pennatuliden,’ p. 161) in addition to the sexual “ zooids.”
In my descriptions I have employed the term “ internode ” for
the hard joints, aud “ soft joints ” for the intermediate ones, as being
more appropriate and more conformable to the botanical usage than
the “ jo in t” and “ internode” employed by Gray {I.e.) to designate
these parts respectively.
The new genus Psilacabaria presents an exception to the usually
strongly marked bilateral symmetry in the arrangement of the
external parts of the corallum in this family.
MELITODES.
Melitæa, Lamarck, Mém. du Mus. d'Hist. Nat. i. p. 410 (1815).
Melitodes, Verrill, Bull. Mus. Comp. Zool. i. p. 38 (1863).
Axis, both hard and soft joints, traversed by longitudinal canals ;
cortical spicules of two kinds, viz. larger, fusiform, verrucose, and
smaUer, nodular. As above stated, the first of these characters only
distinguishes Alelitodes from Clathraria and Psilacabaria among
Melithæidæ.
32. Melitodes alb itin cta.
( P l a t e XXXAHI. figs. C-G" ; P l a t e X X X V III. figs. h, V .)
Corallum slight, branching in one plane. Stem slender, internodes
circular in section ; joints oval, little thicker than the internodes and
about half their length. Branchlets slender, undulating, almost all
anastomosing, forming chiefly elongate meshes. Diameter of internodes
of the larger main branches 3 millim., of terminal branchlets
1 millim. Colour of general cortex in dry state white, beautifully
speckled with vermilion, th at of verrucæ and the contained polypes
orange-yellow. Cortex very smooth, thin on stem, on terminal
branchlets forming about two thirds of the thickness of the branch.
Verrucæ broad, slightly prominent, arranged in two alternating rows
on each side of the branches, but generally absent from the anterior
and posterior faces ; they are of two sizes, viz. :—(i.) abundant, low,
about -4 millim. in diameter at their base ; (ii.) about one to each
iuternode on an average, more prominent than (i.), measuring about
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