CHROMOSOME STUDIES 181 



For the chromosome conditions in the Oedipodinae and Acri- 

 diinae, I have depended on the figures of Davis ('08). 



In order to show that phenomena similar to those in Chor- 

 thippus may possibly occur in the Locustidae and Gryllidae, 

 I have given figures from Buchner ('09), Davis ('08), and Baum- 

 gartner ('04) and from a paper by one of my students. Miss 

 Carrie I. Woolsey. Here, again, I believe that the great amount 

 of variation in chromosome numbers hitherto described may be 

 due largely to the intimate association of certain chromosomes 

 in some genera or species which in others may remain separate. 



TAXONOMY 



According to Handlirsch ('08), the order Orthoptera includes 

 five families, Acrididae, Locustidae, Gryllidae, Gryllotalpidae 

 and Tridactyhdae. Systematists divide Acrididae into nine 

 subfamilies. Of these, five are found in North America: the 

 Tettiginae (Tettigidae) (figs. 1-6, 9-13, 17, 19, 21), Eumastac- 

 inae, Truxahnae (figs. 7, 8), Oedopodinae (figs. 14, 18, 20, 22), 

 and Acridiinae (figs. 15, 16a, 16b). Representatives of all 

 but one have been used for chromosome study; in addition the 

 Pamphaginae have been studied in Europe. In the present work 

 I have studied more particularly the chromosomes of the first 

 group. For reasons which will be stated further on, I rank the 

 Tettiginae on a par with the Acrididae, rather than as one of its 

 subfamilies, and shall therefore use for them the term Tettigidae. 



1. Taxonomy and chromosomes 



McClung ('05, '07) has advanced to a very considerable ex- 

 tent the contention, first advocated by himself, that a certain 

 degree of parallelism exists between chromosome structure and 

 those characters of the body which systematists recognize as 

 of use in determining the relationships of species, genera, and 

 families. He contends that the degree of relationship may 

 be recognized just as precisely in germ-cell structure as in any 

 other part of the body. As the number of species of Orthop- 



