1880 .] Notes. 349 
rod, which they erett in the parts of the ground below where 
they are strongest. 
Mr. F. P. Perkins, in a paper read before the Society of Public 
Analysts, points out the universal presence of starch. In dust, 
whether suspended in the air or collected from the most varied 
places, this ingredient can always be recognised. The author 
therefore justly contended that, especially in chemico-legal inves- 
tigations, no theories can be founded on its occurrence. 
Two serviceable illuminators on the immersion principle have 
been produced : that by Messrs. Powell and Lealand consists of 
a combination of lenses capable of transmitting a pencil of light 
of 130°: it is connected optically with the lower surface of the 
slide by means of oil of cedar wood. The diaphragm arrange- 
ments are simple and effective ; the movement of a single lever 
permits of the employment of a central pencil, or of one or two 
marginal slots placed at right angles to each other. It is neces- 
sary, for the effective use of this condenser, that the objects 
should be mounted on the under side of the cover glass, and not 
on the slide. Like most illuminators that are of real utility, it 
requires some experience to obtain the best effects ; it is of great 
value in resolving difficult lined tests. The illuminator by Mr. 
J. W. Stephenson, F.R.A.S., consists of a plano-convex lens, 
worked on a i-inch tool, and having a diameter of i*2 inches, 
which is then “ edged down ” to i inch, as being more conve- 
nient in size, and as giving an aperture sufficient for the purpose. 
The upper or convex side of the lens is cut down or flattened, 
so as to give a surface four-tenths of an inch in diameter, with 
which the slide is to be connected, when in use, by a drop of oil 
or water. The upper curved surface of the lens is silvered, and 
beneath the lens a flat silvered plate, one-twentieth of an inch 
thick, and corresponding in size and position with the upper 
flattened surface, is balsamed. A suitable diaphragm can be 
placed one-eighth of an inch or less below the condenser. If 
used with a dry lens of the highest power on a balsam-mounted 
object, the light, unable to pass the upper surface of the covering 
glass, is thrown back on the object, giving opaque illumination : 
on the other hand, with dry objects adhering to the slide, the 
well-known dark ground illumination can be obtained with almost 
any objective. The lens should be accurately constructed, as 
any error in thickness is doubled by reflection. — W. T. Suffolk, 
F.R.M.S. 
Prof. Owen has communicated to the Royal Society an account 
of the gigantic Australian lizard, Megalenia prisca, now extinct. 
The upper jaw appears to have been sheathed with horn, as in 
the tortoise. Upon the head were seven horns. Its closely 
now surviving representative is the diminutive Australian spe- 
cies, Moloch horridus. 
