166 THE CAUSES WHICH PROPAGATE 



tolerably high — " tzi, tzzi." These notes had their origin in an 

 apparatus similar to that just noticed. About 4 mm. from the 

 wing-base the vena subexternomedia in the male is somewhat 

 elevated^ and the ordinary scales which cover it increase in size 

 and thickness^ passing into a lima such as we find in the 

 Saddled Leaf-crickets. This character extends to about 10 mm. 

 from the wing-base, where the vein disperses in a fine network. 

 In respect to a Neartic species. Dr. Scudder says : " Some of 

 the veins in the centre of the wing of the male Arci/j^tera lineafa 

 (one of which he indicates) have a rasp-like surface, upon which 

 the hind thighs are scraped up and down.""^ 



The hyaline-winged Epacromia thalnassia, Charp., according 

 to Yersin, is partial to the plains in Northern Italy, where it 

 haunts the dust and stones. Here the males assemble together, 

 place themselves side by side, move over one another, advance 

 and retire, as if in sport. When one retires he vibrates a single 

 leg, so as to produce for less than half a second a dull and feeble 

 sound. He then takes some steps forward and vibrates the other, 

 and so continues till he meets another individual, when he 

 prolongs his strokes. " Once 1 saw a male vibrate both legs at 

 a time. He was alone, with the head applied to the ground, 

 and the abdomen with the posterior portion of the body raised at 

 an angle of 45°.^^ To observe the stridulation of the ink-lined 

 Parapleuriis typus, Fischer, it is necessary to choose a sunny 

 day, and place oneself in the midst of the continental meadows 

 where they abound. When two or three are gathered together 

 they commence movements with the legs, some long, others short 

 and rapid. The latter only are accompanied with a sound, which 

 is distinct at a short distance, and lasts not more than half a 

 second. Yersin informs us that the males of (Edijooda fasciata, 

 Fab., also move their hind legs, and perhaps produce a sound, 

 which may be said likewise of those of the pink-flushed Caloji- 

 tenus if aliens, Lin. 



But the larger grasshoppers with coloured wings, where the 

 attraction of colour appears to su2:)plant that of sound, as, for 

 example, those of the genus (Edipoda, seem to be mostly incapable 

 of much music. These certainly have the elytral vein previously 

 alluded to raised, and presenting, in common with its fellows, a 

 structure resembling obliquely strung beads, but I have never 



