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THE AMERICAN NATURALIST [Vol. LI 



chirping in unison, Shull was not justified in concluding 

 that the synchronism observed by Dolbear was merely an 

 illusion. If such were the case, it is surprising that so 

 many other excellent observers have also been misled by 

 the same illusion in reporting the music of the snowy tree 

 cricket. For many years I have made a very close study 

 of the stridulations of insects, yet I have noted this syn- 

 chronous chirping in but one other species of those 

 crickets which possess the intermittent habit of trilling. 

 One may frequently hear great numbers of the common 

 field cricket {Gryllus pennsylvanicus) chirping in the 

 fields, but these crickets never show the least tendency to 

 chirp in unison as do th^ snowy tree crickets. The jump- 

 ing tree cricket {Orocharis saltator) is also an intermit- 

 tent triller and may sometimes be heard chirping in great 

 numbers in certain copses, yet the 'illusion" of syn- 

 chronous trilling one somehow never experiences. Like- 

 wise, there appears to be no tendency whatever for the 

 ground crickets, Mio gryllus saussurei, Nemobius fas- 

 ciatus, or Nemobius ambitiosns, to chirp in unison. Many 

 other locusts and katydids, such as Conocephalus ensiger, 

 Conocephalus exiliscanornus, and the common katydid 

 {Cyrtophyllus perspicillatus) produce regular, intermit- 

 tent notes and stridulate in well-defined colonies, yet so 

 far as I have observed the individuals of a species never 

 show the least tendency to stridulate in unison. 



In the south, however, I have heard the t^Ly tree crickets 

 {Cyrtoxipha columbiana) chirping in unison with re- 

 markable precision, producing waves of shrill, rhythmic 

 sound, as in the case of the snowy tree cricket. In this in- 

 stance great numbers of these crickets were located in the 

 branches of a large evergreen holly tree. The shrill notes 

 of this little cricket are delivered with great regularity, 

 as are the low, solemn chirping notes of the snowy tree 

 cricket. This regularity in the delivery of the chi.ping 

 of these two crickets is especially striking when compared 

 with the musical efforts of other chirping crickets, such 

 as (Ecmithus angustipennis, Orocharis saltator, or Gryllus 

 ponisjflraiuais. This sustained regularity in the rate 

 of cliiriiiiiu' of tlie snowy tree cricket has been noted by 



