the Luminosity of the Sea. ROB 



water round it. This animal possessed a great power of con- 

 tracting its body laterally ; and it seemed to me that it was by 

 this power it was enabled to dart so quickly forward in the 

 water. It retained its luminous property for upwards of 

 twelve hours after it was put into a tumbler of clear salt 

 water, d is a more magnified sketch of the front of the body, 

 showing the necklaces and feathery filaments. 



c {Jig, 101.) is evidently one of the same group as the last- 

 described. It consisted also of a pure, transparent, gelatinous 

 body, with four short angular horns projecting from its upper 

 extremities, and in the centre a cylindrical substance, as in 

 the last, but without the beautiful pearl necklace. It was 

 contracted near its lower extremity, bulging out again at the 

 lower end. The body of the animal was surrounded like the 

 other by circular zones; and two short antennae, with a round 

 spot at their summits, appeared on each side, running a short 

 way into the angular horns. This also retained its luminous 

 power a considerable time. Yours, &c. 



Edinburgh, July 20. 1831. W. Baird. 



Art. VI. Additional Remarks on the Luminosity of the Sea. 

 By J. O. Westwood, Esq. F.L.S. &c. 

 Sir, 



My friend, W. Baird, Esq., has placed in my hands the 

 very interesting paper inserted above, upon the luminosity 

 of the ocean (intended for the Magazine of Natural History), 

 for the purpose of my adding any additional observations 

 which may occur to me upon the subject. These additional 

 observations will relate, 1st, to the nature and cause of lumi- 

 nosity of the sea; and, 2d, to the animals observed by my 

 friend belonging to the class Crustacea. 



1. It will be seen, in his former memoir (Vol. III. p. 308.), 

 that Mr. Baird, after stating some of the supposed causes of 

 the interesting appearance in question, adopts the now gene- 

 rally received opinion, which, indeed, he considers as fully 

 established, that animalcules of various kinds, having the power 

 of emitting light, are the true cause and origin of the appear- 

 ance. Let us, however, consider the views taken of the sub- 

 ject by some of the most distinguished naturalists. It is true 

 that Vivian i. Sir Joseph Banks, Dr. Macartney, Mr. J. V. 

 Thompson (p. 260.), Dr. Macculloch, Mr. Vl^oodward(p.285.), 

 as well as my friend Baird, and others, suppose that it origin- 

 ates in luminous marine animals : Dr. Macartney expressly 

 stating, that " the light of the sea is always produced by living 

 animals " {Phil Trans., 1810, vol.ii. p. 290.); Dr. Macculloch, 



