CHROMOSOME STUDIES 203 



chidinae. Cell structure and chromosomes likewise show this 

 relation. The cell has a diameter one-fourth to one-third 

 greater than that of Acridium or Paratettix. The network of 

 the cytoplasm is much looser. 



Figures 91 and 92 show thirteen chromosomes (cf). arranged 

 as usual in six pairs plus the sex chromosomes : two large (6's and 

 5's), two intermediate (4's and 3's), and two small pairs (2's 

 and I's). The sex chromosome {5x) ranks fifth in size. The 

 5's and 6's are more nearly equal than was true in any of the 

 other genera (Tables XV-XIX). Table XX (oogonia and 

 follicle cells) shows a much greater difference between the 5's 

 and 6's. Possibly some error may be the cause of this, as only 

 three cells were used. 



Figures 93 to 99, prophases and metaphases of the first sper- 

 matocyte, show the number and size relations more perfectly 

 than the spermatogonia do. Figure 99 lacks a single pair of 

 chromosomes (4's), due probably to loss in sectioning. It will 

 be seen from these figures and Table XVI that a greater interval 

 in size (8.6) occurs between the 5's and the 4's in Tettigidea 

 than in Acridium (7.8) or Paratettix (5.1). Also the gap be- 

 tween the 2's and 3's is not so great as in these genera. In 

 other words, the intervals which separate the four largest auto- 

 somes are more nearly equal in Tettigidea than in either of the 

 other genera. These relations may be most readily appreciated 

 from Tables I-XX. Figure 100 shows an oogonium. The 

 number of chromosomes is, as usual, fourteen. Size relations 

 are well shown. 



8. Tettigidea parvipennis Morse. This species, in chromo- 

 somes, is so much hke Tettigidea parvipennis pennata that it 

 is impossible to tell them apart. Figures 101 to 103 are of 

 oogonia. The number is fourteen (six pairs plus two sex chromo- 

 somes). The slight inequality of the two largest pairs (6's and 

 5's) is evident, especially in figure 101. In figures 102 and 

 103 no. 5 is foreshortened. This affects the results in Table 

 XX. The 4's and 3's show the usual gradation in size. 



Figures 104, 105, and 107 are spermatogonia with the usual 

 thirteen chromosomes. In figure 106 a large chromosome (no. 



