xxii Proceedings. [November yth, i8g8. 



the chief charactistics of these three tribes, specimens oi Smy?t- 

 ihurus, Lepidocyrtus, Macrotoma, Degeeria and Isotoma were 

 shown in illustration. 



Special attention was called to the peculiar forked springer 

 growing out of the antepenultimate joint of the abdomen, varying 

 very much in size in the various species shown ; to the ventral 

 organ of attachment, which also sometimes acts as a retaining 

 holder for the springer ; and to the scales found on some species, 

 but absent in others. The use of these scales as test objects for 

 microscopical object glasses, and the vexed question of the true 

 interpretation of what was seen, was alluded to. 



Mr. Boyd expressed the opinion that the real character of 

 the markings could only be ascertained by comparison of the 

 markings on the scales of a series of different species. 



Commencing with the Lepisma scale, he showed the longitu- 

 dinal ribs to be on the upper surface of the scale, whilst on the 

 lower surface there are cross ribs, and besides these there is a 

 series of ribs running parallel to the rounded edge of the scale. 



In Macrotoma the longitudinal folds or ribs are uniform 

 and extend, at the lower edge, beyond the edge of the scale. 

 The cross ribs at right angles show as dots, whilst the third set 

 of ribs, very coarse, curved, and few in number, could only be 

 seen in scales the surface of which had been obliterated by 

 moisture. 



In Degeeria the longitudinal ribs are very coarse, and are 

 not continuous in height or thickness, and so give the appear- 

 ance of marks of exclamation. The cross ribs are very faint, 

 being only indicated by dots, and the third series of ribs is only 

 seen near the margin of the scale. 



In Templetonia the exclamation marks are very coarse. 



In Lepidocyrtus, the so called Podura test scale, the markings 

 are very much finer. 



From this set of comparisons one can see that the ex- 

 clamation marks, so difficult to show clearly under the micro- 

 scope, are merely the longitudinal ribs or foldings of the upper 

 urface of the scale. The cross ribs here again are indicated 

 by small intermediate dots. 



