6 TRANSACTIONS—PERTHSHIRE SOCIETY OF NATURAL SCIENCE. 
detected by the lens, and often by the unaided eye, a fine parallel 
striation, an unfailing test of this felspar. The rock has a reddish 
appearance ; this is owing to the oxidation of the iron in the rock. It 
is quite common to find rocks with a reddish tinge on exposed surfaces, 
as at Salisbury Crags at Edinburgh. The rock, under certain con¬ 
ditions of light, has quite a fiery appearance, although the rock is of 
the usual steel-grey colour beneath the surface. The rock, however, 
of the Knapp Quarry has this reddish tinge throughout its entire 
mass as well as on exposed surfaces, showing that the alteration has 
penetrated into the rock. 
To those members of the Society who are fond of field geology 
this portion of our county forms a unique field for observation. It is 
the only locality in the whole of the county where basalt rock is 
found at the surface as a rock mass on a large scale, and it presents 
many landscape features which you will fail to detect in the softer 
rock comprising the Sidlaws proper. 
II.— The Hemiptera-Heteroptera and Heniiptera-Hornoptera^ together 
zvith a list of species occurring in Perthshire. 
By T. M. M‘Gregor. 
(Read 8th Feb., 1894.) 
So little is generally known about these sub-orders of the 
Hemiptera that it may be well to describe in brief outline the 
characteristic features peculiar to them, to explain what the respec¬ 
tive terms signify, and to glance in passing at their habits and life 
history. 
The term Hemiptera is applied to that order of insects comprising 
bugs, plant lice, &c., and signifies “ half wings,” being derived from 
the Greek henii (half) and pteron (a wing). This name w^as doubtless 
suggested by the appearance of the front wings, or elytra, of the 
sub-order Heteroptera, which are coriaceous at the base and mem¬ 
branous at the apex. 
The word Heteroptera signifies “ diverse whngs,” from the Greek 
heteros (diverse) and ptero 7 i (a wing); and it is to the members of 
this sub-order that the appellation “ Bug ” is usually applied. They 
are chiefly characterised by the membranous extremities of the wings, 
wEich overlap each other. The neck is more or less distinct, and the 
head usually prominent, while the rostrum, or beak, arises from the 
front part of the head. The legs are slender, and sometimes very 
long, being formed respectively for running, jumping, swimming, &;c. 
