202 KANSAS UNIVERSITY SCIENCE BULLETIN. 



Students of the Orthoptera have divided the family Acrididse 

 into nine subfamilies, of which only four are found in the 

 United States. Material from these four has been studied, and 

 I feel convinced that one of these subfamilies should be re- 

 moved from the group. The other three are manifestly related, 

 and so closely do two of them grade together that there is much 

 dispute as to the disposition of certain genera. The third sub- 

 family is definitely marked, and it is sufficient for the sys- 

 tematist to find a distinct spine on the prosternum of an acridian 

 in order to place it in the subfamily Acridiinse. Within this 

 division of the family there are a large number of subgroups, 

 the principal one being the Melanopli. This includes many ex- 

 tensive genera, of which one, Melano'plus, contains over 120 

 species in the United States. Another genus of this group, 

 Hesperotettix, is of wide distribution but embraces only seven 

 species. Of these latter I have studied three and they seem to 

 be plainly marked in their body characters. I have thought 

 that, by selecting a variable genus and another of the same 

 group that is more stable, it might be possible to determine the 

 general nature of the changes associated with variability. 

 Both of these lines of investigation are being pursued, but it 

 seemed best to consider first the nature of the less variable 

 form, particularly since there is one chromosome that can 

 definitely be identified throughout the genus. 



This latter circumstance I consider extremely fortunate, for 

 the occurrence of the same number of chromosomes within 

 the family raises the presumption that they are serially homol- 

 ogous almost to a certainty ; the discovery of the same element 

 in three species of a certain genus amounts to a positive proof 

 of this fact. Particularly is this true when it is understood 

 that the homologous elements really represent two of the chro- 

 mosome complex. With this definite structure indubitably 

 marked in the different species, I felt that I had opened up be- 

 fore me an opportunity of unusual promise, but one which 

 would require long and tedious labor for its development. I 

 regret that more has not been accomplished, but what has been 

 done is sufficient to indicate the fruitfulness of the investiga- 

 tion. 



Briefly, then, we may note that, so far as our observations 

 have gone, all the species of the genus Hesperotettix have 

 within their first spermatocytes a multiple chromosome, a 

 hexad, consisting of the accessory chromosome and one of the 



