NATURAL HISTORY. 



633 



so improbable and inconsistent, 

 that one might be led to doubt 

 this insect's existence, particularly 

 as it does not appear to have 

 been ever seen, except by Eke- 

 berg, the captain of an East India- 

 man, from whom Linnaeus learnt 

 its history. 



I now proceed to the descrip- 

 tion of those luminous animals 

 that have been discovered by the 

 Right Honourable Sir Joseph 

 Banks, Captain Horsburgh, 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 occa- 

 sioned the phsenomenon ; the one, 

 a crustaceous insect which he 

 called the cancer fulgens ; the 

 other a large species of medusa, 

 to which he gave the name of pel- 

 lucens. 



The cancer fulgens bears some 

 resemblance to the common 

 shrimp ; it is, however, consider- 

 ably less, the legs are furnished 

 with numerous setae. The light 

 of this animal, which is very bril- 

 liant, appears to issue from every 

 part of the body. 



The medusa pellucens mea- 

 sures about six inches across the 

 crown, or umbella; this part is 

 marked by a number of opake 

 lines, that pass ofiF from the centre 

 to the circumference. The edge 

 of the umbella is divided into 

 lobules, which succeed each other, 

 one large and two small ones al- 

 ternately. From within the mar- 

 gin of the umbella, there are 

 suspended a num bcrof long cord- 



shaped tentacula. The central 

 part of the animal is opake, and 

 furnished with lour thick irre- 

 gularly-shaped processes, which 

 hang down in the midst of the 

 tentacula. 



This zoophile is the most splen- 

 did of the luminous inhabitants 

 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 Captain 

 Horsburgh, he remarks that the 

 luminous state of the sea between 

 the tropics is generally accompa- 

 nied with the appearance of a great 

 number of marine animals of va- 

 rious kinds upon the surface of 

 the water ; to many of which he 

 does not, however, attribute the 

 property of shining. At other 

 times, when the water which gave 

 out light was examined, it appear- 

 ed only to contain small particles 

 of a dusky straw colour, which 

 dissolved with the slightest touch 

 of the finger. He likewise ob- 

 serves, that, in Bombay, during the 

 hot weather of May and June, he 

 has frequently seen the edges of 

 the sea much illuminated by mi- 

 nute sparkling points. 



At sun-rise on April 12, 1793, 

 in the Arabian sea, he perceived 

 several luminous spots in the 

 water, which conceiving to be ani- 

 mals, he went in the boat and 

 caught one. It proved to be an 

 insect somewhat resembling in ap- 

 pearance the wood-louse, and was 

 about one-third of an inch in 

 length. When viewed with the 

 microscope, it seemed to be form- 

 ed by sections of a thin crustace- 

 ous substance. During the time 

 that any fluid remained in the 



