90 



camera in each case, to afford the standard of comparison. The 

 drawing was then corrected in detail, by portions set off with the 

 higher power, which were found to match the enlarged drawing with 

 tolerable accuracy; in this way a very fair representation of the 

 scale and its markings was produced. The cross stria?, when viewed 

 with a twelfth of a hundred-and-ten degrees aperture, and illu- 

 minated with a quarter of sixty degrees, used as an achromatic 

 condenser, and adjusted well to focus, came out under a power of 

 eight-hundred-and-twenty-five diameters in beaded lines, on which 

 protuberances were distinctly seen; these latter, when focused at 

 their summits, appeared as brown dots. The longitudinal stria?, 

 under the same circumstances, have likewise a somewhat corrugated 

 appearance, but not so marked, and at the upper surface similar dots. 

 In Plate VIII. fig. 2, accompanied by a scale of ten-thousandths of an 

 inch, is represented a portion of the stria? at the lower focus, as seen 

 with a power magnifying nineteen-hundred diameters, though the 

 drawing is made for convenience, to a scale of forty-four-hundred to 

 one. The scale when viewed from the under side with this power, 

 exhibits the lower membrane as slightly undulating, probably from 

 its being dry. 



Some of my friends have thought that the constricted appearance 

 of the cross stria?, just described, is due to the overlaying pigment- 

 cells ; this, in my opinion, is not correct ; as I have convinced 

 myself by careful and repeated examinations, more especially from 

 the under side, that the stria? themselves are really beaded ; it is true 

 that the pigment-cells correspond very exactly in position with the 

 stria?, which is very remarkable ; but, in some of the deeply coloured 

 scales there is a granulated appearance covering the entire surface 

 of the scale very uniformly, in which the constricted appearance of 

 the striae is even more apparent. Hence it would appear that the 

 peculiarity in the markings of the Amathusia Horsfieldii is due, not 

 to their consisting of minute scales, but to the superposition of pig- 

 ment-cells exactly over the beaded striae; the transverse markings 

 exhibiting the appearance most strongly. I do not see that there is 

 anything in this assertion which is antagonistic to Mr. Bowerbank's 

 view of the structure of similar scales ; for though he did not remark 

 that any of the stria? were constricted, yet that they may be so, and 

 still be tubular, is evident ; indeed, as regards the number of layers 

 and general structure of the scales of Lepidoptera, my experience 

 agrees fully with his view. The number of beads in the cross striae 

 of the Amathusia are from two to four ; they are not globular, but, 



