CHROMOSOME STUDIES 183 



The fundamental number in the Locustidae seems to be some- 

 what in doubt. Miss Stevens ('12) found thirty-seven in Ceu- 

 thophilus. In Jamaicana subguttata, unicolor, and fiava (Wool- 

 sey, '15) the number is thirty-five. McClung ('02, '08) and 

 Otte ('07) found the number in five genera to be thirty-three. 

 Buchner ('09) found thirty-one in Decticus. Other cases 

 (Steiroxys, Davis, '08) may be shown to have thirty-one, owing 

 to the presence of compound chromosomes. The numbers most 

 frequently found seem to be thirty-three and thirty-one. The 

 extremely large number in Ceuthophilus may indicate a sub- 

 family difference; in Jamaicana, a tribal difference. 



Opinion as to the number of chromosomes in Gryllidae is un- 

 settled. The most frequent is thirty-one or thirty-three (cf). 

 It is quite possible that in Gryllidae also occur cases of com- 

 pound chromosomes, since eight or ten V's are present in species 

 with low numbers (Baumgartner, '04; Gutherz, '09; Payne, 

 '12). The tree-crickets (Baumgartner, '11) have 13 (c/') and 

 14 (9); Stenopelmatus (Stevens, '05), forty-six. Such large 

 variations as the last may indicate wide taxonomic difference. 



2. Taxonomic characters compared 



Before describing chromosomes, it is best to compare taxo- 

 nomic characters of Tettigidae with those of three subfamilies 

 of the Acrididae, also the characters of the genera and species 

 I have studied within the Tettigidae. 



The Tettigidae are more distinctly marked off from the 

 subfamilies of Acrididae than these are from one another (com- 

 pare figs. 1-6, 9-13 with figs. 7, 8, 14-16). The dividing line 

 is not clearly marked between the Oedipodinae (fig. 14) and the 

 Truxalinae (figs. 7, 8), and is but slightly more marked between 

 either of these and the Acridiinae (fig. 15). 



The chief distinguishing characters of Tettigidae are the 

 extremely developed apical process of the pronotum (figs. 1-6, 9), 

 the absence of pulvillus (fig. 12), and extreme reduction or ab- 

 sence of elytra (ely., in figs. 1, 3, 4, etc.). Over against this 

 in the subfamilies of the Acrididae the pulvillus is present (fig. 



