Observations upon Luminous Animals. 93 
The formuias 4 and 6 having for denominator the sine 
of (A—A’) M. Gauss concludes that if A = A’; that is 
to say, if the two stars have been observed in the same 
vertical. or in different verticals of 180°, the errors dh 
dW’ will have a prodigious influence. 
The same consequence may be drawn from my first for- 
mula, for-it bears for its denominator the sine W, and in 
the same case W = 180, and sin W = Olike sine (A — A’). 
This consequence, however, is subject to some remark- 
able exceptions 
- For, suppose that A = A’, that is to say, the two stars 
Nave been observed in the- same vertical line, a single alti- 
tude will suffice, forh —h’ = D,u = 180—V &e.—u + 
“VY = 180? = W, w will then be known without error, the 
formula (3*) dg = dh cos A — ducosh sin A is. reduced 
‘thereby io the term dh cos A. 
4 Miers [To be continued.] 
& 
F Ai4 
KVILI. Observations upon Luminous Animals. By James 
‘i Macartney, Esq. 
[Concluded from p. 35.] 
° 
ive remarkalsle property of emitting light during life ‘is 
only met with amongst animals of the four last classes of 
modern naturalists, viz. mollusca, insects, worms, and zoo- 
hytes. ; 
The mollusca and worms contain each but a single Jumi- 
nous species ; the pholas dactylus in the one, and the nereis 
noctiluca in the other. - 
Some species yield light, in the eight following genera of 
insects : elater, lampyris, fulgora, pausus, scolopendra, can- 
cer, lynceus *, and limulus. The luminous species of the 
genera lampyris and .fulgora are more numerous than is 
generally supposed, if we may judge from the appearance 
of Juminous organs to be seen in dried specimens. 
Amongst zoophytes we. find that the genera medusa, 
beroe+, and pennutula, contain species which afford light. 
The only animals which appear to possess a distinct or- 
* The animal discovered by Riville off the coast of Malabar in 1754 is 
certainly a testaceous insect, and appears to belong to the genus lynceus of 
Me Tie luminous zoophyte for which Peron has lately instituted the new 
genus pyrosoma, appeare to me to bea beroe, and only worthy of a specific 
distinction, aii) 
ganization 
