250 Transactions of the 



of different thicknesses and refractive powers, or internally stopped, 

 reflected or dispersed. The more the structure retains this charac- 

 teristic, the greater the difiiculty to traverse with confidence the 

 shoals of conjecture. 



In venturing to bring before the notice of the Fellows of the 

 Koyal Microscopical Society, the subject of the general and particu- 

 lar construction of some of the scales of the Lepidoptera, after the 

 recent and valuable contributions by Mr. Mclntire, Mr. Jos. Beck, 

 Mr. Wenham, and Dr. Woodward, as well as the very interesting 

 article by one of your secretaries, Mr. Slack, contributed to the 

 pages of 'The Student,' No. 1, February, 1870, some apology is 

 necessary ; but the minute construction of the scales of the Lepi- 

 doptera being, so far as I can judge, still open to inquiry, and the 

 subject so full of interest in reference to the views advanced by Dr. 

 Pigott, &c., let me ask your indulgence to be permitted to lay before 

 you the results of a careful, if not very extended, examination, ac- 

 companied by coloured drawings of such portions as touch upon the 

 question of beads or beaded structure, as well as the general ar- 

 rangement of parts in relation to the same, in the " Test scale " of 

 Lepidocyrtus. 



If these researches have led me to differ from some authorities 

 in various particulars, the results are stated with diffidence, and 

 with the desire further observations may be undertaken by those far 

 more able than myself to compass the inquiry ; but if the evidence 

 can, in any way, tend to place the subject in a more satisfactory con- 

 dition, or increase the testimony of others, it will amply repay for 

 the trouble and time it has taken. Mr. Slack in the before-mentioned 

 pages of ' The Student ' has furnished the opinions of many observers: 

 not to lengthen unnecessarily this article, I shall allude but briefly 

 to them in passing, and refer to his pages for particulars. 



The announcement made by Dr. Pigott, in the pages of the 

 Society's Journal for December, 1869, on the structure of the Podura 

 scale, " Test scale," Le])idocyrtus curvicollis* took many of us by 

 surprise — and naturally so, considering this scale to have for years 

 been so continually under observation, and the special study of 

 that accurate observer and artist, the late Eichard Beck ; therefore 

 to him our thanks are due for rousing us from our wonted apathy, 

 and for pointing out fresh methods for obtaining increased magnifi- 

 cation, claiming some advantages over high-power objectives and deep 

 eye-pieces. 



To such a contrivance he has given the name " Aplanatic 

 Searcher," and by its means has obtained results which abound with 

 interest ; though, to the minds of many observers, they are received 

 with considerable doubt, or referred to optical effects of an illusory 

 nature. 



* Vide p. 300. 



