58 ILLINOIS BIOLOGICAL MONOGRAPHS [452 



usual type of the group and are world wide in distribution. The 

 patterns to the right of these are those with the basal spot and the 

 two spots along the inner border, shown on the map by the stippled 

 area; this includes a number of pilosity groups and thus represents 

 considerable diversity. The group in which the middle cross band (4) 

 is oblique in the reverse direction as compared with that which is usual 

 in the group as a whole, is shown by small circles. This is essentially 

 confined to the Oriental region. There are a few species in Africa 

 which show this and which appear somewhat related on the basis of 

 pilosity, but circles are omitted. The group of species and patterns 

 shown at the extreme right and represented on the map by the short 

 oblique lines constitute a group divided between the Oriental and 

 Australian regions. 



An over-lapping of the various types in the Oriental region is evi- 

 dent. This would place the center for the group in that region but 

 several African species appear to be most primitive from the standpoint 

 of kind of patterns shown. It accordingly seems best to consider that 

 the lands adjoining the Indian Ocean constitute the center of distri- 

 bution of the group. 



GENERAL DISCUSSION 



The evidence which must support any conclusions drawn is of 

 such a character and drawn from so many sources that the presentation 

 of a few lines of evidence and the conclusions forthcoming from them 

 can best follow the general presentation of data and minor conclusions 

 on the preceding pages. Since color and color pattern are quite dis- 

 tinct so far as laws governing them are concerned, the discussion of 

 the two will be separated. 



PATTERN TENDENCIES 



Under this head we are concerned with (a) the original type, (b) 

 the most characteristic elements and combination of original charac- 

 ters, (c) general laws of pattern modification applicable to groups of 

 species, (d) laws applicable to particular species, and (e) laws appli- 

 cable to subdivisions of species. 



As has been noted the number of directions in which modification 

 has preceded are numerous and any statement of such directions is 

 difficult and has led other authors to make general statements regarding 

 the modification of patterns which were general enough to apply to a 

 large number of species. 



The earliest account of variation in the color, or markings or the 

 patterns of tiger beetles is that of Dr. Geo. H. Horn (1892). He took 



