JOURNAL 



OF THE 



ROYAL MICROSCOPICAL SOCIETY. 



DECEMBER, 1911. 



TRANSACTIONS OF THE SOCIETY. 



XXII. — I. On the Structure of Scales from Thermobia domestica 



(Packard). 



By James Strachan. 



(Read June 28, 1911.) 

 Plate XXIV. 



Thermobia domestica. — This " bristle-tail " is one of Lepismatidse — 

 closely allied to, but distinct from, the common " silver-fish " insect 

 (Lepisma saccharina). It is probably an introduced species in the 

 British Islands, and is found chiefly in the interior of buildings, 

 close to warm places such as stoves and hot-water pipes. During 

 the past few years the present writer obtained a large number of 



EXPLANATION OF PLATE XXIV. 



Fig. 1.— Normal scale from Thermobia domestica x 400 ; showing longitudinal 



tubes and latter " broken " up at margin. 

 „ 2.— Scale from T. domestica partially immersed in gummy residue from oil of 



turpentine ; showing upper half of scale with longitudinal tubes and 



lower half with radial tubes, x 400. 

 „ 3.— Scales from T. domestica x 400; showing effect produced by crossing two 



scales. 

 „ 4. — Reduced photograph of cuneate markings produced by illuminating the 



model obliquely. 

 Figs. 5, 6, 7 and 8. — Diagrams showing the evolution of cuneate markings from 



beaded markings as observed by slowly focusing through the scale of 



T. domestica at margin. Fig. 5, Beaded markings. Fig. 6, Twisted 



beads. Fig. 7, "Clubbed" or "exclamation" markings. Fig. 8 



Cuneate markings. 



Dec. 20th, 1011 3 a 



