TRANSACTIONS OF SECTION D. 1047 
lamented naturalist, gives a fascinating picture of. a long, delicate, simple 
Gorgonian which came up in immense numbers in the trawl from 600 fathoms 
off the Spanish coast. He conjures up this Gorgonian forest as an animated corn- 
field waving gently in the slow tidal current, and glowing with a soft diffused 
phosphorescence, scintillating and sparkling on the slightest touch, and now and 
again breaking into long avenues of vivid light, indicating the paths of fishes or 
other wandering denizens of these enchanted regions. Professor Moseley thinks 
that this brilliant phosphorescence of the Alcyonarians may be regarded as an 
accidental production, but that it may be of occasional service. Further, that the 
deep sea is at any rate lighted up by these Alcyonarians, which would thus form 
luminous oases round which animals with eyes might possibly congregate.1 
The last group of the Ccelenterates, the Ctenophora, are even more conspicuous 
than the foregoing in regard to luminosity. It is indeed long since the Abbé 
Dicquemare descanted on Cydippe (Plewrobrachia) and Suriray on Beroé, while 
subsequent authors have made it clear that the majority of this group are phos- 
phorescent. In our own seas, as Professor Allman observes, Beroé at various 
stages is one of the most prominent luminous forms during certain seasons, Their 
enormous numbers make their effects more striking, though the intensity of 
the phosphorescence is less than that of the Medusz. Quiet seas like Bressay 
Sound and the Firth of Forth are occasionally covered by a dense layer of 
these animals, Professor Allman found that Zeroé did not phosphoresce if 
suddenly taken from light into darkness, but that after they had remained about 
twenty minutes in obscurity they became luminous. Considerable variety exists in 
this respect at St. Andrews, some emitting light at once, others showing none. It 
is probable that this uncertainty is connected with the hygienic condition of the 
individuals. 
In foreign seas many brightly luminous species are met with. Thus Professor 
A, Agassiz? describes Mnemiopsis Letdyi as ‘exceedingly phosphorescent, and 
when passing through shoals of these Medusze, varying in size from a pin’s head 
to several inches in length, the whole water becomes so brilliantly luminous that 
an oar dipped up to the handle can plainly be seen on dark nights by the light so 
produced; the seat of the phosphorescence is confined to the locomotive rows, and 
so exceedingly sensitive are they that the slightest shock is sufficient to make them 
plainly visible by the light emitted from the eight phosphorescent ambulacra.’ 
The same author* mentions that Leswewria has a very peculiar bluish light of an 
exceedingly pale steel colour, but very intense. Giglioli, again, found that the 
beautiful riband-like Cestus shone with a reddish yellow light, but in Hucharis 
the latter was intensely blue.* 
While many of the preceding group are pelagic at all periods of their existence, 
the luminous star-fishes are in their adult condition members of the bottom fauna, 
The larval stages of the brittle-stars, however, are passed at the surface of the 
water, where it is probable they add their quota to swell the ranks of the phos- 
horescent types. Amongst the first to note this property in the brittle-stars was 
rofessor Viviani, who found on the shores of Genoa a little brittle-star which he 
termed <Asterias noctiluca, and which probably is identical with the Amphiura 
elegans of Leach. Péron likewise mentions the phosphorescence of his Ophiwra 
phosphorea. Sir Wyville Thomson observed in the ‘ Porcupine’ that the light from 
Ophiacantha spinulosa was of a brilliant green, coruscating from the centre of the 
disk along the rays and illuminating the whole outline of the starfish. More 
recently, Professor Panceri of Naples has re-examined the phosphorescence of the 
species described by Viviani, and he finds that though with the first momentary 
glow the whole ray is lit up with a greenish light, the luminous points corre- 
1 Notes of a Naturalist on the ‘Challenger, p. 590. 
2 North American Acalephe, p. 20. Cambridge, 1865. 
3 Op. cit. p. 24. 4 Op. cit. p. 495-96. 
5 Phosphorescentia Maris, Genoa, 1805, p. 5, tab. i. figs. 1-2. He observes : 
“Speciem hanc radiate instar stelle scintillas in marinis aquis excitasse, quas 
electrico fluido adscripserunt, admodum probabile est.’ 
5 Depths of the Sea, p. 98. 
