64 



EVOLUTION IN COLOR-PATTERN OF THE LADY-BEETLES. 



3061 a. Coccinella difficilis Crotch. 



Distribution: Utah. 



Although the pattern of this species (fig. 47) is very close to that of 

 C. monticola var. alutacea, it is probably entitled to specific rank. This is 

 because of its small size and the fact that the two elements of the median 

 row of elytral spots vary in the direction of greater pigmentation by 

 increase in general dimensions rather than by confluence. Specimens are 

 as yet too few to make its status and relationship clear. 



B B > 



60 



FIG. 60. Variation of elytral pattern in C. monticola var. alutacea and biguttala. 

 FIG. 61. Pronotal pattern of C. monticola var. alutacea. a, a single specimen. 



3061 b. Coccinella suturalis Casey. 



Distribution: Colorado. 



This is very clearly a derivative from C. monticola var. alutacea by the 

 addition of the pigmented suture a repertoire variation. Its specific rank 

 rests largely upon the reduced height of the elytra. 



FJG. 62. Variation in color-pattern in C. prolongata. 

 a, 6, c, from Cheney, Wash.; rf, from Utah. 



3061. Coccinella prolongata Crotch. 



Distribution: Kansas to Pacific Coast. 



The elytral pattern is essentially that of C. monticola var. alutacea, 

 from which it is probably derived, but with the pigment still further 

 reduced. The pronotal pattern is striking, and although there is some in- 

 tergradation, it is apparently interrupted (fig. 62). The essential char- 

 acteristic is not only the prolongation of the white area of the pronotum, 

 but the spindle shape of the central portion of the back area cephalad as 

 well as caudad. Its nearest allies have the black pattern extending along 

 the cephalic edge for half its width. 



