upon Luminous Animals , 265 
on which I had previously collected a number of luminous 
points, several of them were liberated, and became distinctly 
visible in their natural element, by placing the glass before a 
piece of dark coloured paper. They were observed to have a 
tendency to come to the surface of the w 7 ater, and after the 
glass was set by for some time, they were found congregated 
together, and when thus collected in a body, they had a dusky 
straw colour, although individually they were so transparent, 
as to be perfectly invisible, except under particular circum- 
stances. Their substance was indeed so extremely tender 
and delicate, that they did not become opaque in distilled 
vinegar or alcohol, until immersed in these liquors for a con- 
siderable time. 
On examining these minute globules with the microscope, 
I found that they were not quite perfect spheres, but had an irre- 
gular depression on one side, which was formed of an opaque 
substance, that projected a little way inwards, producing such 
an appearance as would arise from tying the neck of a round 
bag, and turning it into the body. 
The motions of these creatures in the water were slow and 
graceful, and not accompanied by any visible contraction of 
their bodies. After death they always subsided to the bottom 
of the vessel. 
From the sparkling light afforded by this species, I shall 
distinguish it by the name of medusa scintillans. 
The night following that, on which I discovered the pre- 
ceding animal, I caught the two other luminous species. One 
of these I shall call the beroe fulgens. 
This most elegant creature is of a colour changing between 
purple, violet, and pale blue ; the body is truncated before. 
