202 WM. EEES B. ROBERTSON 



placing Acridium and Parattetix in one subfamily and Tettigidea 

 in another. These relationships are shown in the chromosomes, 

 and in the size of cells. The 5's and 6's are very large and differ 

 considerably in size. The inequality between them (22.0 to 

 23.6, Tables XI, XIII) is, however, not nearly so marked as in 

 Acridium (22.48 to 28.14, Tables I, VIII). Again, the range 

 of size from largest to smallest is not nearly so great as in Acridium 

 (29.4 to 10.0, Table IX; compare also figs. 78 to 82 with 67, 68). 

 The sex chromosome in Paratettix cucculatus (3x)is slightly 

 larger (13.9) than in Acridium (11.9). In length it comes near- 

 est the 3's, so is designated by Sx instead of Ix or 2x, as in Acrid- 

 ium. However, it is, like Acridium, near the size of the small- 

 est group (I's and 2's). It may, as in Acridium, be distinguished 

 in spermatogonia by its 'woolly' appearance (fig. 82). The 

 measurement (17.2 is too high, as usual in first spermatocytes. 



6. Paratettix texanus Hanc. This species (figs. 85-90) ^ is 

 similar to cucculatus, but the range in size of chromosomes 

 (first spermatocyte) is somewhat less. This may be due to the 

 greater diameter and consequent shortening of the 5's and 6's. 

 In the second spermatocyte the range is about the same as in 

 the spermatogonia of cucculatus, though the 5's differ (22.0 

 in cucculatus; 20.9 in texanus). 



The sex chromosome is about third in size and slightly larger 

 than in the preceding genus. Its rank, according to length in 

 first spermatocytes, is not correct, since it is longer and of less 

 diameter, compared with autosomes, than it is in the sperma- 

 togonia or in the second spermatocytes. The measurements 

 of first spermatocytes were, therefore, not used. 



Paratettix is, therefore, distinguished from Acridium by 

 smaller cells ; by a less range in extreme lengths of chromosomes ; 

 by slightly larger sex chromosome; and by a smaller difference 

 in the length of the two largest chromosomes. 



7. Tettigidea parvipennis pennata Morse. Tettigidea is in 

 body structure much farther from Acridium than is Paratettix, so 

 far, in fact, that it is placed in a different subfamily, the Batra- 



2 Figures 88 to 90 are from a slide of Paratettix texanus leucocephalus Nabours, 

 kindly furnished me by Dr. Mary T. Harman. 



