CHROMOSOME STUDIES 185 



do not necessarily indicate close relationship with Locustidae 

 and Gryllidae, but" they do show the wide divergence of the 

 Tettigidae in these respects from what we find commonly in 

 the subfamilies of Acrididae. 



Upon the basis of these visible external and the grosser inter- 

 nal characters, we would at once separate what was formerly 

 known as the Acrididae into two groups, on the one hand the 

 Tettigidae and on the other the Truxalinae, Oedopodinae, and 

 Acridiinae. 



The Tettigidae are in turn divided into four subfamilies, the 

 Cladonotinae, Metrodorinae, Tettiginae, and Batrachidinae. Of 

 these we have represented in the United States only the last two. 

 Of the genera which I have studied, two (Acridium [Tettix] 

 and Paratettix) belonging to the former group and one (Tetti- 

 gidea) to the latter. We should, therefore, expect to find among 

 these three genera two more nearly related to each other in 

 chromosome characters, than either of them is to the third. 

 Before taking up chromosome characters, we shall consider 

 the body characters. 



The subfamilies Tettiginae and Batrachidinae may be distin- 

 guished from each other by the following points: 



Tettiginae Batrachidinae 



1. Anterior femora compressed, cari- 1. Anterior femora broadly sulcata 



nate above. above. 



2. Vertex, viewed from the dorsal 2. Vertex large and projects much 



side (figs. 3, 4, 5b, 13a), extends in front of the eyes (figs. 10, 11). 



either scarcely to, or slightly 

 beyond, the eyes. 



3. Antennae composed of twelve to 3. Antennae composed of twenty-two 



fourteen segments. segments (in Tettigidea). 



4. Pronotum in front truncate (figs. 4. Pronotum in front not truncate, 



lb, 2b, 3, 4, 5b, 6). but produced above the head; 



anterior dorsal margin angulate 

 (figs. 10, 11). 



5. Dorsum flat, may be at same time 5. Dorsum not flat, but obtusely tecti- 



slightly carinate or cristate. Me- form. Median carina conspicu- 



dian carina inconspicuous. ous. 



6. Humeral angles of pronotum ob- 6. Humeral angles of pronotum an- 



tuse (fig. 3, ang. hum.). gulate. 



