upon Luminous Animals . 263 
between the tropics, is generally accompanied with the ap- 
pearance of a great number of marine animals of various 
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 appeared only to contain small particles of a dusky straw 
colour, which dissolved with the slightest touch of the finger. 
He likewise observes, that in Bombay, during the hot weather 
of May and June, he has frequently seen the edges of the 
sea much illuminated by minute sparkling points. 
At sun rise on April 12, 179S, in the Arabian sea, he per- 
ceived several luminous spots in the water, which conceiving 
to be animals, he went in the boat and caught one. It proved 
to be an insect somewhat resembling in appearance the wood 
louse, and was about one third of an inch in length. When 
viewed with the microscope, it seemed to be formed by sec- 
tions of a thin crustaceous substance. During the time that 
any fluid remained in the animal, it shone brilliantly like the 
fire fly. 
In the month of June in the same year, he picked up 
another luminous insect on a sandy beach, which was also 
covered with a thin shell, but it was a different shape, and 
a larger size than the animal taken in the Arabian sea. 
By comparing the above description with an elegant pen 
and ink drawing which was made by Captain Horsburg, and 
accompanied his paper, I have no doubt that both these insects 
were monoculi ; the first evidently belongs to the genus 
limulus of Muller ; I shall therefore beg leave to distinguish 
it by the name of limulus noctilucus. 
My pursuits, and the state of my health, haring frequently 
M m 2 
