66 



EVOLUTION IN COLOR-PATTERN OF THE LADY-BEETLES. 



Genus OLLA Casey. 



The color-pattern in this genus is so diverse in its elements and lines of 

 variation from Coccinella that I believe that it is entitled to more than 

 the subgeneric rank which Leng gives it. It has stronger resemblances to 

 Neoharmonia ampla in its color-pattern than to any Coccinella. 



3065 a. Olla abdominalis Say. 



Distribution: Indiana to Texas, Arizona to California. 



The crescentic shape of the subsutural intermediate spot has its parallel 

 in Neoharmonia venusta and ampla and one specimen of H. convergent. 

 The variation in the color-pattern of the pronotum is given in fig. 67. 



Flu. 67. Variation of pronotal pattern of 

 O. abdominalis. '< -mode. 



Var. semilunaris, n. var. 



The subsutural and intermediate spots of the intermediate row are fused and 

 extended towards the apex to make a bowl-shaped mark (fig. 68). This ex- 

 tension is a unique feature, for it is not an equilateral enlargement nor a 

 confluence of spots, but a determinate extension in one direction. Arizona 

 and Texas. 



Var. minuta Casey. 



The elements of the intermediate row and the apical spot are confluent, but with 

 reentrant angles (fig. 68). Brownsville, Texas. 



FIG. 68. Variation in elytral pattern in O. <t'> /'n ''/'/'-. /, var. minuta; g, h, var. semilunnrix. 

 FIG. 69. Variation of color-pattern in O. playiata. All from Arizona. 



3065 b. Olla plagiata Casey. 



This is the melanic derivative of Olla abdominalis (fig. 69) and may be 

 found to be intergenerating. In the meanwhile it is best considered dis- 

 tinct. The Florida specimens differ, Casey says, as well as those from 

 Las Vegas, Mexico, but the difference is slight and, in the lack of a large 

 series, they will not be described here. 



