Mr. Macartney’s Observations 
262 
I now proceed to the description of those luminous animals 
that have been discovered by the Right Honourable Sir Joseph 
Banks, Captain Horsburg, and myself. 
On the passage from Madeira to Rio de Janeiro, the sea 
was observed by Sir Joseph Banks to be unusually luminous, 
flashing in many parts like lightning. He directed some of 
the water to be hauled up, in which he discovered two kinds 
of animals that occasioned the phenomenon ; the one, a crus- 
taceous insect which he called the cancer fulgens ; the other, 
a large species of medusa, to which he gave the name of 
pellucens. 
The cancer fulgens bears some resemblance to the common 
shrimp ; it is howe'ver considerably less, the legs are furnished 
with numerous setae. The light of this animal, which is very 
brilliant, appears to issue from every part of the body. 
The medusa pellucens measures about six inches across the 
crown or umbella ; this part is marked by a number of opake 
lines, that pass off from the center to the circumference. The 
edge of the umbella is divided into lobules, which succeed 
each other, one large and two small ones alternately. From 
within the margin of the umbella, there are suspended a 
number of long cord-shaped tentacula. The central part of 
the animal is opake, and furnished with four thick irregularly 
shaped processes, which hang down in the midst of the 
tentacula. 
This zoophyte is the most splendid of the luminous inha- 
bitants of the ocean. The flashes of light emitted during its 
contractions, are so vivid as to affect the sight of the spectator. 
In the notes communicated to Sir Joseph Banks by Cap- 
tain Horsburg, hekremarks that the luminous state of the sea 
