4 
316 MICROSCOPY, 
This discovery would not only prove the existence of man in 
Miocene times, but of man who had already made some progress, 
at least, in art. Mr. Calvert assures me that he feels no doubt 
whatever as to the geolegical age of the stratum from which these 
specimens were obtained. 
Of course I am not in a position myself to express any opinion 
on the subject ; but I am sure that the statements of so competent 
an observer as Mr. Calvert will interest your readers.—Sir Joun 
Lusgock, in “ Nature.” 
MICROSCOPY. 
AMPHIPLEURA PELLUCIDA IN Dots.— A sy objective was made 
by Tolles to my order and finished on the 12th of March, 1873. 
The angle of aperture as invoiced by Mr. Stodder is 165°. From 
my measurements I think the objective is correctly named by the 
maker. At the extreme open point it is a good ,4, dry. The 
screw-collar has twelve divisions: by turning it eight divisions it 
is adjusted for uncovered wet, and four divisions remain to adjust 
for cover for immersion work. It works through covering glass of 
about 34, of an inch; but it is better to use thinner glass, or mica, 
to enable the observer to focus through specimens. 
With lamplight and the ~ the resolution of Amphipleura pel- 
lucida is better than I have before seen. Using ordinary daylight 
Vibriones, Bacteria, ete., are well defined, especially when a Kelner 
eye-piece is used as a condenser. ‘ 
. With sunlight and the ammonia-sulphate of copper cell, Suri- 
rella gemma yields longitudinal striæ, and, as the direction of the 
light is changed, rows of “ hemispherical bosses” as described by 
Dr. Woodward. 
With the same illumination specimens of Amphipleura pellucida, 
mounted dry, by Norman, were resolyed and counted with perfect 
ease and remarkable plainness, the striæ being still distinctly visi- 
ble with No. 3 eye-piece, draw-tube extended six inches and power 
upwards of 10,000 times. It is with hesitation that I remark fur- 
ther that the 3, has resolved the lines of Amphipleura pellucida 
into rows of dots, for the “ beaded” structure of the easier test, 
Surirella gemma, is still doubted by some experienced microscop- 
ists. But facts are stubborn things, and the facts are that with 
Wenham’s parabola as an illuminator the dots are seen, and with 
e = either the paraboloid or the Amici prism longitudinal lines much 
