On the Phosphorescence of Marine Invertebrata. 69 
ted by means of an excentric bearing for the end of the axis, to 
which the circle is attached, and which is readily turned, within 
the declination box, until the adjustment is found to be correct, 
and then secured. A clock is attached to the telescope for keep- 
ing the object in the field of view, and an important improve- 
ment has been made in the manner of communicating the motion 
to the hour circle. The thread to fit the tangent screw, is cut in 
the edge of a ring, detached from the hour circle, and merely 
pressed against it on a conical bearing, by the elasticity of a thin 
brass plate, which is secured by four screws, that give the requi- 
site friction. 
This detached arrangement permits the telescope to be moved 
in any direction, while in connection with the clock, and obviates 
the necessity of clamping and unclamping, thereby greatly dimin- 
ishing the danger of injury to the instrument. 
Arr. VIIIL—On the Phosphorescence of some Marine Inver- 
tebrata ; by M. A. De QuatTREFacEs, 
Szconp Parr.— General observations on Phosphorescence. 
1. Description of the phenomenon.—It would be useless to 
repeat here all the details given by travellers; I will confine 
myself to some remarks on my own observations. 
The phosphorescence of the sea has appeared to me under two 
different forms: 1st, a result of scintillations more or less nu- 
merous, always isolated, and not giving at all the idea of a liquid 
In itself luminous: 2nd, a general glow more or less uniform, 
the phosphorescent substance seeming to be dissolved in the 
water itself. ae 
In both cases, phosphorescence is equally a result from living 
animals, directly emitting the light, but the species which pro- 
duce the phenomenon are different. 
A. I have often observed the first mode of phosphorescence on 
monds, but these sparks, always very brilliant, and appearing at 
the same instant, never communicated a general glow to the wa- 
er. They remained completely isolated, and were distinct from 
the dark surface of the sea.. At Brehat, St. Malo, and St. Vaast, I 
observed similar facts. ‘The fishermen whom I questioned, all 
assured me that in these regions, the sea never presented a difler- 
ent appearance; the young men who had never left their native 
