50 



EVOLUTION IN COLOR-PATTERN OF THE LADY-BEETLES. 



3046 b. Hippodamia dispar Casey. 



Distribution: Colorado. 



Of this very rare species I have seen only the type in Major Casey's col- 

 lection, the specimen in the U. S. National Museum, and the one in the Leng 

 collection (fig. 34). The 3 specimens show some variation in the rotundity 

 of 4 + 5, but the combined spot is in all cases much rounded. The rounded 

 enlargement of the 4+5 area in H. cockerelli points strongly to a derivation 

 of H. dispar from H. cockerelli. A large series might reveal an amount of 

 intergradation which would bring them into one species. But at present 

 the few specimens known are distinct. 



FIG. 34. Color-pattern of H. dispar from Colorado. 

 FIG. 3o. Variation of elytral pattern in H. sinuata. 

 a, variety crotchi . 



b = mode; b to e, from Alaineda, California; 



3049. Hippodamia sinuata Mulsant. 



Mulsant's description seems to apply to the same beetles later named 

 H. trivittata by Major Casey, and his type came from the same locality. 

 This Calif ornian species (see fig. 35), with the vittae complete, is, however, 

 distinct from the other beetles often called H. sinuata, which have the 

 vittae very strongly bowed in the apical half of the elytra, or incomplete 

 or lacking; these latter are properly placed in H. spuria. 



Mr. Nunenmacher informs me that H. sinuata is restricted to the salt- 

 marshes, and in my collection in California I failed to find them outside of 

 the marshes. It is this fact, together with the lack of intergrades, that 

 causes me to consider them specifically distinct. This isolation by its 

 decrease of interbreeding would have afforded the opportunity to establish 

 intersterility. 



Var. crotchi. 



The suture black for only one-third of the length. One specimen from San Fran- 

 cisco in the collection of Mr. Leng. 



3050. Hippodamia tredecimpunctata Linnaeus. 



Distribution: Europe, United States, and Canada. 



This species is the least variable of all the widely ranging species of 

 Hippodamia. Yet large series show variation (see figs. 36 to 38) . This is 

 parallel in part to that given for Europe by Weise (1899) and Mulsant 

 (1846). The names and letters employed by them will be used. While 



