42 E. I. Nichols— Optical Method for the 
pleura curving inward below, giving a cylindrical form. Pleura 
broadly rounded at their extremities on the anterior face, but 
somewhat angular above and marked by a central ridge below, 
and by a backward curving, transverse ridge across the widest 
part. Caudal flap large, forming a triangular plate on each 
side, the first and second joints short sub triangular; marginal 
plate of the flap thickened, narrow and elongate; central plate 
the other portions unknown. Thoracic limbs very slender and 
only of moderate length, the second joint laterally compressed, 
making the height nearly double the width; other joints 
apparently cylindrical. Abdominal limbs known only by 
their second (?) joints, which appear to be triangular in form, 
widening below, flattened and plate-like in character or slightl 
convex on the anterior face. (In one case only, a single thread- 
like appendage can be seen, as if projecting from the outer 
of the carapace, originating at the lower anterior angle and 
passing upward and backward, with a bifurcation at the ante- 
rior third of its length. Surface of the abdomen essentially 
smooth. Caudal flaps marked by impressed lines increasing 
in number and fineness from above downward. 
Art. VIIL—Upon an Optical Method for the Measurement of High 
Temperatures ; by KE. L. NicHois, Ph.D. (Gottingen). 
IN a previous paper* a series of experiments upon the nature 
and intensity of the light emitted by glowing platinum were 
described. It is proposed in this article to discuss more fully 
the results then Sutin and to develop from them, so far as 18 
at present possible, an optical method for the measurement of 
* On the Character and Intensity of the Rays emitted by Glowing Platinum, 
vol. xviii, Dec., 1879. 
