CHROMOSOME-GROUPS OF METAPODIUS AND BANASA. 305 



in a somewhat plastic condition as regards the chromosomes, and 

 presents certain variations in the number of the larger chromosomes 

 that need not here be described, since they do not affect the rela- 

 tions to be considered. Alone among all the Coreidee thus far 

 examined, the three species of Mctapodins possess a typical pair of 

 idiochromosomes along with a typical pair of ///-chromosomes - 

 a fact which proves the validity of the distinction between these 

 two forms of chromosomes drawn in my second study. The 

 idiochromosomes are distinctly, though not greatly, unequal in 

 size ; and as usual among the Hemiptera, they remain separate as 

 univalents in the first maturation division, but conjugate at the end 

 of this division to form an unequal bivalent. In the greater num- 

 ber of individuals (which maybe classed together as " Type A ") 

 the first division shows 1 3 chromosomes (Fig. I , b] and the sec- 

 ond 12. In the most usual arrangement the two idiochromo- 

 somes (/and /) lie in the first division not far apart, outside an 

 irregular ring formed of nine larger bivalents, in the position 

 typical of the odd chromosome in other coreids. Near the cen- 

 ter of the ring lies a very small ///-chromosome bivalent (;;z), 

 which as in so many other cases is formed in the late prophases 

 by conjugation of its two members. The thirteenth chromosome 

 is the small unpaired univalent 5-chr6mosome (s) which divides 

 like all the others in the first division but passes undivided to 

 one pole in the second division. In three of the seven males 

 I have, this chromosome is of the same size as the ///-chromo- 

 somes. In two individuals of the same type it is somewhat 

 larger, though markedly smaller than the large bivalents. In 

 the remaining two males (which constitute "Type B ") the 

 .y-chromosome is wanting in all the cells, whether spermatogonia 

 or spermatocytes. In these individuals the first spermatocyte 

 division uniformly shows 12 chromosomes (Fig. i,e) and the 

 second 1 1, the grouping being otherwise more or less nearly simi- 

 lar to that in the first type. 



tion probably cannot now be resolved, since the original specimens of Montgomery's 

 material are not in existence. I think it probable that two different species have 

 been under observation, and there is some reason to suspect that Montgomery's ma- 

 terial may have been Euthoctha galeator. This case illustrates the extreme impor- 

 tance, in work of this kind, of preserving every individual from which cytological 

 material is taken. 



