COLOR PATTERN OF VENTRAL SURFACE. 



85 



variation of all of the species mentioned above, no other variations being 

 known excepting asymmetrical abnormalities. 



The variation of the color pattern upon the ventral side is a metameric one, 

 dominated by the principles of metameric control of variation in such struc- 

 tures, as is shown in the beginning of increase of color at the anterior end 

 and decrease at the posterior end. The variations are in complete accord- 

 ance with the general laws of progressive development in a metameric series 

 which begins anteriorly, and of regressive development which begins poste- 

 riorly. Upon individual segments the variations move distalward and caudal- 

 ward in increase, or proximalward and cephalward in reduction, and these 

 directions of modification are, as far as this material is concerned, absolutely 

 inflexible, being most rigorously controlled by the structure and constitution 

 inherent in the race. 



Quantitatively, the variations of the ventral surface present points of some 

 interest. These have been seriated, as have the variations on other parts of 

 the body, on a scale of value indicating the proportion of light to dark color. 



Table 28. Variation in the proportion of light to dark color on the ventral surface of 

 L. multitaniata, L. oblongata, L. intermedia, L. rubicunda, L. decemlineata, L. juncta, 

 and L. defecta. 



This table shows clearly the range of variation in this color pattern. L. 

 multitceniata is the most variable and rubicunda the least. The ventral sur- 

 faces in species where this part is unicolorous are not as variable as the uni- 

 colorous dorsal parts of the body. As far as is known, they show no points 

 of interest. 



