423] COLORS OF TIGER BEETLES— SHELFORD 29 



In C. hirticollis (Figs. 141 to 145) the pigment appears to begin 

 almost uniformly over the elytron except for the weaker places repre- 

 senting the ontogenetic markings. The lighter places are between the 

 lines of the tracheae. There are cross bands at the base of the elytron, 

 the middle one usually more -or less clearly connected with the distal 

 end of the adult cross hand 3. Usually there is a spot opposite the end 

 of this band between the media and the cubitus and usually another 

 set of dots stretches across the elytron between the band 2 and band 

 These bands of a secondary nature are not present in the later stages or 

 if so not marked. The longitudinal lines become weaker as time goes 

 on and the markings, except those that are to be permanent, gradually 

 disappear; those in the region of the base are last to go. In some cases 

 lighter longitudinal lines are divided into spots. 



A late stage in C. 12 guttata shows the same longitudinal stripes 

 and cross bands. Throughout the series longitudinal stripes seem to 

 be most marked in the earlier stages but become partially divided Later 

 and are rarely or never continuous but nearly always broken into spots. 

 This is shown in nearly all the figures presented and the conclusion 

 which seems warranted is that the longitudinal stripes are a more defin- 

 ite character than the cross band, though neither occurs alone. The 

 fact of a combined cross and longitudinal system of unpigmented areas 

 is the one which comes forcefully forward in the entire study though 

 there are irregularities present. Further, one sees a close resemblance 

 between the ontogenetic patterns and those of the African and Eurasian 

 species on which the analysis of the pattern was based. One notes also 

 the close correspondence between the spots shown in the general plan 

 presented in figure 48, plate V, and those occurring in the ontogeny 

 of the patterns of common North American species. This would seem 

 to establish the plan of the pattern as well as could be hoped. 



The entire set of evidence presented tends to show that the simplest 

 type of pattern in the Cicindelas is a pattern of spots lying in lines be- 

 tween the chief longitudinal tracheal trunks and falling into cross 

 bands of which there may be seven. In ontogeny these are subject to 

 some variations but such a description fits the general relations found 

 better than anything else that can be stated. Such a type of pattern, 

 which is of the character that is commonly called primitive, is what 

 might be expected among insects. The wings are usually characterized 

 by longitudinal veins which are thickened and hardened and often pig- 

 mented. These veins are connected transversly by cross veins which are 

 much more diversified in the insect group than are the longitudinal ones 

 and which are also much more subject to individual variation. Traehi 

 usually occupy the longitudinal veins but not always the cross veins. 

 hence in the insects which have actual cross veins there is not a neces- 



