224 THE CAUSES WHICH PROPAGATE 



adapted a notation to the notes of the New South Wales species. 

 He says, " The most common is the incessant drumming-, but it 

 is not confined to this. The ' Taz, ziz, ziz ' is often interrupted 

 by ' Ohoi, ohoi, ohoi/ varied to ' Whocky, whoeky, whocky/ 

 and the noise ceases. Sometimes a prolonged note of ' Alrite, 

 ah-ite, alrite ' is heard, varied to ' Ohoe, ohoe, ohoe/ the last note 

 being prolonged, followed by ' Whocky, whocky, whocky •' in 

 very shrill tones; then 'Ziz, ziz, ziz ^ continues for some time, 

 followed by a sound of ' Yocky, yocky, yocky,^ after which the 

 din suddenly ceases.^' This observer noticed they were capable 

 of modulating the sound and varying its intensity. Thopha 

 saccata, probably the most powerful of Australian Cicadse, 

 and often observed in this country in naturalists' 

 windows, cries " Awock, awock, awock,''^ and then 

 commences a deafening drumming and chirping, 

 to which the vibration of the air in the little 

 bell-shaped drum-covers (e) must contribute. 

 Cj/stosoma Sandersil, another kind, resounds in 

 the orange groves during the short reign of 

 twilight, or in the gloom previous to a thunder- 

 storm, like a lond guttural " r," often so loud as 

 Thopha SACCATA. to be painful to the ear. The Australian Cicadse 

 begin their song at the end of October, T. 

 saccata sings from December 15th to 28th. 



But the maximum size and din of these oratorio performers 

 of the insect race is reached in districts such as Guiana, and the 

 islands of the Eastern Archipelago, scorched by the equatorial 

 sun, where the notes, no more likened to the vigour of the 

 minstreFs lyre, are compared to the blast of the clarion, and the 

 performers themselves termed trumpeters. " After lying for 

 a week off Panama,^^ says Mr. G. F. Mathew, R.N., in a 

 late contribution to the Entomologist's Monthlij Magazine on 

 the habits of Cicada gigas, " we were not at all sorry on the 

 afternoon of the 27th February, 1874, to raise our anchor, 

 and, favoured by the afternoon breeze, drop down under sail 

 to the island of Tobago, where we arrived at six o^clock, and 

 took up a position within a convenient distance of the landing- 

 place. Soon afterwards, while standing on deck admiring the 

 beauties of the island, with its immense profusion of tropical 



