CHROMOSOME STUDIES 199 



(figs. 29-33). It is true that there is here some abnormal length- 

 ening of some of the double chromosomes, as may be seen by 

 comparing 5 and 6 of figure 62, but this is not so great as in some 

 cases of first spermatocyte chromosomes in granulatus. It 

 seems safe to say that there is a striking similarity in the chromo- 

 some ratios of the two species (compare Table VII with I and 

 V), although there are enough differences to serve as a basis 

 for specific distinction. 



3. Acridium ornatus Harris. Only two cells (figs. 65, 66) 

 from this species are shown. They are unfavorable for deter- 

 mining accurately the relative lengths of the chromosomes, 

 since the latter are in prophase and differ in the degree of conden- 

 sation to which each has advanced. This probably accounts 

 for the extreme difference between the two smallest pairs (Table 

 VIII, 1, 2). Chromosome no. 1 (figs. 65, 66) is much more 

 contracted than either 2, 3, or 4. A similar precocious conden- 

 sation is seen among the smaller tetrads in Syrbula and Chor- 

 thippus (figs. 149, 163). The sex chromosome is precociously 

 condensed and therefore appears shorter (Table VIII) than it 

 otherwise would be. Chromosomes 2, 3, and 4, on the con- 

 trary, appear more slender (fig. 66) than nos. 1, 5, and 6, and 

 therefore relatively longer than they otherwise would be, while 

 the latter are relatively shorter (Table VIII). In spite of these 

 discrepancies, the sizes characteristics of the family, subfamily, 

 and genus may be readily recognized. It seems justifiable to 

 say that here, again, the ratios are sufficient to put this species 

 into the genus Acridium rather than Paratettix or Tettigi- 

 dea. The material is too scant to warrant going into specific 

 differences. 



4- Acridium obscurus Hanc. This species (figs. 2a, 2b, 67- 

 77; Tables IX, X) is not so closely related to granulatus as is 

 incurvatus. The germ cells of the male have thirteen chromo- 

 somes. I have not examined those of the female nor the somatic 

 cells. 



The chromosome size relations, as in ornatus and incurvatus 

 are sufficiently similar to those of granulatus to place obscurus 

 within the genus Acridium. They agree with the other species 



