ODYNERUS. 147 



character is a regular zoological one, for it advances together with 

 a thick and short thorax in both genera, 



Examples of the second modification. — (Local geographical 

 modification, not peculiar to one or several genera, but quite 

 special to one country.) 



a. As a very striking example in this way, one could hot choose 

 better than in the group of Chilian Yespidse. This forms quite 

 a remarkable collection of species, all having the same very 

 striking appearance. Indeed, all the Chilian Yespida?, to what- 

 ever genus they belong, have the same peculiar livery; black, 

 with long black hair and whitish ornaments; with rufous or black 

 feet, rufous wings obscure at the apex. This livery (with its 

 varieties) is so striking, that one may at the first look distinguish 

 a Chilian species, and this facies is to be found in all the genera. 

 Odynerus, Gayella, Ctenochilus, Alasto?', etc. The forms of the 

 body, although quite variable, are also very characteristic in their 

 appearance. In the Chilian true Odynerus they even become so 

 very peculiar that we have been forced to make for them the 

 Division Hypodynerus. Nevertheless this is not properly a 

 zoological group, as it is again found in all the genera, but is 

 evidently only a stamp of the country which every species of any 

 genus seems to receive when it has the citizenship of that 

 country. 



b. The species which populate the continuation of the same 

 region in the north, that is, the occidental side of the Andes of 

 Ecuador and New Granada, have also a peculiar facies, still 

 similar to that of Chili, but more approximate to the common 

 type of Odynerus. They are still hirsute with long black pile, 

 black-velutinous, but the ornaments are golden-yellow; the wings 

 are no longer ferruginous. The same character is also apparent 

 in other genera (f. i. Pachymenes ventricosa). 



c. In the Antilles the Odyneri are more marked, and have 

 common forms. They take a rich livery, with numerous orange- 

 yellow bauds and spots. The same modification may be noticed 

 in all the other genera of Yespida? in this region, even in the 

 social wasps. 



d. In the Mexican region there are to be found types, with 

 dull rufous colors and with the margin of the 2d abdominal seg- 

 ment channelled and reflexed ; the Stenodyuerus become quite 

 abundant, with a velutinous body (0. huastecus, otomitus, etc), 



