628 



SCIENCE. 



[N. S. Vol. XXIV. No. 620. 



We have also in our range a striped form, 

 trivitiata, hardly distinguishable from vittata. 

 Thus unstriped and unspotted or striped 

 or spotted, all seem good patterns in the eyes 

 of selection. To me, it is as clear as the 



Fig. 9. Frequency polygon of the variation in 

 elytral pattern of 1,005 specimens of the Cali- 

 fornia flower beetle, Diabrotica soror, collected 

 at San Jose, California, twenty miles south of 

 the Stanford University campus, October and No- 

 vember, 1905. 



significance of any fact in nature is clear, that 

 the change in our locality in Diabrotica soror 

 from a beetle species of typical twelve-spots- 

 free pattern to one of eight-spots-free and two 

 irregular transverse blotches in place of the 

 middle four spots is not due to natural selec- 

 tion. 



As to the third explanation, that of de- 

 terminate variation, I have to say, simply, 

 that there remains of our possible three ex- 

 planations, one, which is that of determinate 

 variation. But, we must note, if determinate 

 variation is the explanation of this change in 

 Diabrotica soror it is a determinate variation 

 which is occurring only, apparently, in our 

 particular locality. For in series of speci- 

 mens of this bettle collected in other parts 

 of California no such change seems to be 

 going on, the old twelve-spots-free form being 

 plainly the modal type. For example, in a 

 series of 405 specimens collected in Santa 

 Rosa, which is about sixty miles north of 

 Stanford University, there are twice as many 

 individuals with all spots free as of those with 

 middle spots fused. (See Fig. 8 and caption.) 

 And in a series of 1,005 individuals collected 

 at San Jose, which is twenty miles south of 

 Stanford University, nearly 49 per cent, are of 

 the twelve-spots-free type and only 30.5 per 

 cent, of the middle-spots-fused type. 



Why the species should be changing on our 

 university campus and not changing in the 

 regions south and north of us is a mystery 

 whose solution I do not even dare to guess at. 

 This solution must have to do with the cause 

 of the variation of the species on our campus. 

 But if one asks what is this cause, what it 

 is that is producing determinate variation in 

 Diabrotica, or in any other species, I have, in 

 this connection, only to refer to a statement 

 in the beginning of this note, which is to the 

 effect that prior to any attempt to explain 

 how determinate variation might be produced 

 it is advisable to attempt to determine if de- 

 terminate variation really exists. Is there 

 determinate variation? 



Vernon L. Kellogg. 



Stanford Univeesity. 



discovery of an early type of man in 



NEBRASKA. 



In a circidar mound recently opened on a 

 Loess hill north of Florence, near Omaha, 

 ISTebraska, various skeletal parts, and eight 

 human skulls of a primitive type were ex- 

 posed. The credit of the discovery belongs 



