SCALES 



977 



in only termed the ' battledore ' scales, from their resemblance in 

 form to that object (fig. 724, a). These scales, which occur in the 

 males of several genera of the family Lycasnidas, and present a 

 considerable variety of shape, l are marked by narrow longitudinal 

 ribbings, which at intervals seem to expand into rounded or oval 

 elevations that give to the scales a dotted appearance (fig. 725) ; at 

 the lower part of the scale, however, these dots are wanting. 

 Dr. Anthony describes and figures them as elevated bodies, some- 

 what resembling dumb-bells or shirt-studs, ranged along the ribs, 

 and standing out from the general surface. 2 Other good observers, 

 however, whilst recognising the stud-like bodies described by Dr. 

 Anthony, regard them as not projecting from the external surface 

 of the scale, but as interposed between its two lamellae ; 3 and this 

 view seems to the Author to be more conformable than Dr. Anthony's 

 to general probability. 



The more difficult ' test scales ' are furnished by little wingless 

 insects ranked together by Latreille in the order Thysanura, but 



FIG. 724. Scales of Pol yominat us Argus 

 (azure blue) : a, battledore scale ; b, 

 interference striae. 



FIG. 725. Battledore scale of 

 Polyommatus Argus (azure 

 blue). 



now separated by Sir John Lubbock, 4 on account of important 

 differences in internal structure, into the two groups Collembola and 

 true Thysanura. Of the former of these the Lepismidce constitute 

 the typical family; and the scale of the common Lepisma saccha- 

 rina, or 'sugar-louse,' 5 very early attracted the attention of 



1 See Watson, foe. cit. 



- ' The Markings on the Battledore Scales of some of the Lepidoptera ' in Monthly 

 Microscopical Journal, vol. vii. 1872, pp. 1, 250. 



5 See ' Proceedings of the Microscopical Society,' op. cit. p. 278. 



4 See his Monograph of the Collembola and Thysanura, published by the Ray 

 Society, 1872. 



"' This insect may be found in most old houses, frequenting damp warm cupboards, 

 and especially such as contain sweets ; it may be readily caught in a small pill-box, 

 which should have a few pinholes in the lid; and if a drop of chloroform be put 

 over the holes the inmate will soon become insensible, and may be then turned out 

 upon a piece of clean paper, and some of its scales transferred to a slip of glass by 

 simply pressing this gently on its body. 



3 R 



