( lxxxix ) 



The inheritance of an excessively small local colour 

 variation in A Hawaiian wasp. — Prof. Poulton said that 

 his recent address (May 25, 1916) to the Linnean Society on 

 the inheritance of small variations had suggested the follow- 

 ing striking evidence to Dr. K. C. L. Perkins, D.Sc, who 

 had permitted him to bring it before the Entomological 

 Society, and had kindly lent the series of specimens exhibited 

 to the meeting. Dr. Perkins' paper " On the Colour-groups 

 of the Hawaiian Wasps," in Trans. Ent. Soc, 1912, p. 667, 

 and Proc. Ent. Soc, 1912, p. lvi, might be consulted for 

 further examples of local colour variation. 



" If you were to look at my series of Odynerus molohaiensis, 

 Perk., from the intermediate islands Maui and Molokai, and 

 that of 0. xerophilus, Perk., from Oahu, you would find that 

 the former varies from a black-bodied insect to one with two 

 yellow abdominal bands and some thoracic spots, all sorts 

 of slight intermediates being present. Just beyond the point 

 where the development in colour of mololcaiensis ends, the 

 Oahuan form 0. xerophilus begins, so that the distinction 

 between them at this point is of the most trivial character 

 (far less than that which separates the extreme varieties of 

 molohaiensis itself), and under ordinary circumstances would, 

 I think, by any hymenopterist be called a ' small variation.' 

 Yet it is possible to distinguish absolutely every Oahu example 

 {xerophilus) from any of the others (molohaiensis) by the fact 

 that the 2nd abdominal band of the former always extends 

 far enough forward (i. e. is broad enough) to include distinct 

 punctures, while that of molohaiensis never does so. I doubt 

 whether there is any other constant character to distinguish 

 these forms ! Yet this trifling difference is so perfectly 

 inherited it has never been found to break down ! 



" The fact is that the Oahu form (xerophilus) is always 

 associated with other species with bands well developed like 

 its own, while the other mixes largely with black-bodied 

 species or such as have only inconspicuous or subobsolete 

 bands, not noticeable in life. 



" It would seem that the presence of a certain width of band 

 in the one case, and in the other of a lesser width or even total 

 absence of banding, must be of great importance in the life of 



