636 



ANNUAL REGISTER, 1810. 



arched manner from the circum- 

 ference, towards the centre of the 

 animal : an opakeirregular-shaped 

 process hung down from the mid- 

 dle of the umbelia : when this part 

 was examined with a lens of high 

 powers, I discovered that it was 

 inclosed in a sheath in which it 

 moved, and that the extremity of 

 the process was divided into four 

 tentacula, covered with little cups 

 or suckers, like those on the ten- 

 tacula of the cuttle-fish. 



This species of medusa bears a 

 striking resemblance to the figures 

 of the medusa hemispherica, pub- 

 lished by Gronovius and Muller ; 

 indeed it differs as little from these 

 figures, as tliey do from each 

 other. Its luminous property, 

 however, was not observed by 

 these naturalists ; which is the 

 more extraordinary, as Muller ex- 

 amined it at night, and says it is 

 so transparent that it can only be 

 seen with the light of a lamp. If 

 it should be still considered as a 

 distinct species, or as a variety of 

 the hemispherica, I would propose 

 to call it the medusa lucida. 



In this species, the central part 

 and the spot round the margin are 

 commonly seen to shine on lifting 

 the animal out of the water into 

 the air, presenting the appearance 

 of an illuminated wheel; and when 

 it is exposed to the usual percus- 

 sion of the water, the transparent 

 parts of its body are alone lu- 

 minous. 



In the month of September, 

 1805, I again visited Heme Bay, 

 and frequently had opportunities 

 of witnessing the luminous ap- 

 pearance of the sea. I caught 

 many of the hemispherical and 

 minute species of medusa, but not 

 one of the bcroe fulgens. I ob- 



served that these luminous animals 

 always retreated from the surface 

 of the water, as soon as the moon 

 rose. 1 found also, that exposure 

 to the day-light took away their 

 property of shining, which was 

 revived by placing them for some 

 time in a dark situation. 



In that season I had two op- 

 portunities of seeing an extended 

 illumination of the sea, produced 

 by the above animals. The first 

 night I saw this singular phseno- 

 menon, was extremely dark; many 

 of the medusa scintillans and me- 

 dusa hemispherica had been ob- 

 served at low water, but on the 

 return of the tide they had sud- 

 denl3' disappeared. On looking 

 towards the sea, I was astonished 

 to perceive a flash of light of 

 about six yards broad, extend from 

 the shore, for apparently the dis- 

 tance of a mile and a half, along 

 the surface of the water. The 

 second time that I saw this sort of 

 light proceed from the sea, it did 

 not take the same form, but was 

 diffused over the surface of the 

 waves next the shore, and was so 

 strong, that I couldfor the moment 

 distinctly see my servant, who stood 

 atalittle distance from me; healso 

 perceived it, and called out to me 

 at the same instant. On botli 

 these occasions the flash was visi- 

 ble for about four or five seconds; 

 and, although I watched for it a 

 considerable time, I did not see it 

 repeated. 



A diffused luminous appearance 

 of the sea, in some respects dif- 

 ferent from what I have seen, has 

 been described by several naviga- 

 tors. 



Godeheu de Riville saw the sea 

 assume the appearance of a plain 

 of snow on the coast of Malabar. 



