532 TRANSACTIONS OF SECTION D. 
a cuttle-fish, unfortunately greatly damaged. I was so struck by the singularity 
of its form and the brilliance of its colour that I at once secured it, and, showing 
it to the fishermen, asked whether they were acquainted with it. Upon their 
replying in the negative I called their special attention to it, and offered a hand- 
some reward for the next specimen secured, either alive or in good condition, and 
then passed on to other fishermen and repeated my promise. Shortly afterwards 
I was summoned and shown a specimen clinging to the net, which I seized and 
placed in a vessel of water. At that moment U enjoyed the astonishing spectacle 
of the brilliant spots, which appeared upon the skin of this animal, whose remark- 
able form had already impressed me: sometimes it was a ray of sapphire blue 
which blinded me; sometimes of opalescent topaz yellow, which rendered it still 
more striking; at other times these two rich colours mingled their magnificent 
rays. During the night these opalescent spots emitted a phosphorescent brilliance 
which rendered this mollusc one of the most splendid of Nature’s products. Its 
existence was, however, of short duration, though I had placed it in a large vessel 
of water. Probably it lives at great depths.’ 
The species thus referred to was Histiotewthis bonelliana, which we shall have 
occasion to refer to in the sequel. 
The next observation, so far as I am aware, was made by Professor Chun (4), 
on board the ‘ Valdivia’ during the German deep-sea expedition, on a form which 
he has called Thawmatolampas diadema. ‘The specimen captured lived long 
enough to allow of a photograph being made of it whilst in a state of functional 
activity, and the appearance it preseuted is thus described by the observer :— 
‘Among all the marvels of coloration which the animals of the deep sea 
exhibited to us nothing can be even distantly compared with the hues of these 
organs. One would think that the body was adorned with a diadem of brilliant 
gems, The middle organs of the eyes shone with ultramarine-blue, the lateral 
ones with a pearly sheen. Those towards the front of the lower surface of the 
body gave out a ruby-red light, while those behind were snow-white or pearly, 
except the median one, which was sky-blue. It was indeed a glorious spectacle.’ 
Finally we have the genera Heteroteuthis and Sepiola the phosphorescent 
properties of which were seen last year by Dr. W. T. Meyer (32) and Dr. W. 
Marchand in the Zoological Station at Naples. 
This short list comprises all the actual observations on the luminosity of these 
animals; in these, however, the photogenic function has been definitely associated 
with special organs, and it is by comparison with these that other organs in other 
species have been regarded as having the same significance. 
The history of the anatomical examination of these organs dates back only to 
the early nineties, and, so far as I can ascertain, the right of priority of the dis- 
covery rests with Professor Joubin (22), who made a communication to the Société 
scientifique et médicale de l'Ouest at Rennes on February 3, 1893, a brief account 
of which was published by the Société de Biologie of Paris on the 10th of the 
same month: this communication related to Histioteuthis riippelli, and in it 
attention was called to Vérany’s observation quoted above. Sections of the 
organs of Abraliopsis were exhibited at the Gottingen meeting of the German 
Zoological Society and at the Nottingham meeting of this Association in the 
same year (13). Successive memoirs by Joubin (23-27) and others followed, and 
in 1903 Professor Chun (5) delivered an address to the German Zoological Society 
at Wiirzburg in which he gave a masterly survey of the whole subject, brought 
forward instances of similar organs previously overlooked, and showed the great 
variety in structure, uot only in the organs of different species, but even in organs 
of one and the same individual. 
More or less adequately authenticated Juminous organs have now been recorded 
in no fewer chan thirty-three species of Cephalopoda, and it may be convenient here 
to give a list of these, with a concise indication of the position in which the organs 
in question occur. 
