431] COLORS OF TIGER BEETLES— SHELF ORD 37 



aud monteiroi (Figs. 276 and 277). These belong to groups which nor- 

 mally have them, but thej' almost never occur in groups which do not 

 show them in a majoritj^ of members. Considering the compoients of 

 the three spots, the anterior central spot {Bi, Fig. 49, PI. V) is a part 

 of the basal cross baud / clearly shown in figure 179. The anterior one 

 in stripe C, figure 48, plate V, appears to be a fusion of spots Ci and 

 C2 and the posterior one of C3 and C4 as a rule, though sometimes the 

 posterior one is C4 and the anterior one Cl.2, figure 165. There is a 

 tendency indicated by variation to drop oiit these markings in many 

 species. In flexuosa usually C 1.2, i. e., the basal sutural spot, is first 

 to go. In others this is not true as a nde, as shown in 261, 276, 277 

 and 280. On the other hand there is no species in which these are 

 present and other markings absent. These facts indicate that these 

 spots show a tendency to disappear first, leaving the types of pattern 

 without them, ilore rarely they may unite to form a band which may 

 persist in the extremely modified forms, figures 151, 160, and 167. One 

 of the characteristic types of marking which seems to belong to almost 

 the entire group showing the typical middle band, is the oblique shift- 

 ing of the cross band which makes the humeral lunule. 



The tendency toward obliqueness of the middle band of the typical 

 forms seems quite general in many groups but by no means iiniversal, 

 and is sho\^m by some species in all the groups, and hence is illustrated 

 in all the groups of figures : 157, 163, 222. 227, 273, 276. 288, 299, 451, 

 33.5, 336, 342, 411, and 417. 



In other groups another tendency seems to be present, namely to- 

 ward a sharp forward-bent angle on the middle band (Fig. 482) figures 

 209, 206, and many others in which the usual combinations have not 

 been affected are sho^vn in plate XIII. On the other hand scarcely a 

 species in plate XII shows this tendency except figure 150. Figures 

 292 and 293, plate XV, 339, plate XVI^i and others related show the 

 same tendencj'. It is shown in the patterns of the Australian group 

 (Figs. 394 to 396, PI. XVII) where a middle band involving different 

 elements occurs, and is particularly conspicuous and characteristic in 

 some of the Mexican and South American species (Figs. 428 to 434, PI. 

 Xr\"III) where it is the chief distinguishing feature. In the, group as 

 a whole the most striking tendency is for the markings to disappear, 

 beginning in the proximal anal region of the elytron and usually leaving 

 the more posterior distal markings present. But to this tliere are many 

 exceptions in which the central marking on the elytron is the only one 

 left. (See figures 255, plate XIV; 222 to 231, plate XIII; and 206.) 



Another tendency manifested in many species is the extension of 

 the white; it is seen to crop out in all groups from any starting point 

 which is in existence and to proceed from tlie spots characteristic of 



