MONOGRAFH OF THE WASPS OF BRmSH INDIA. 477 



character in this genus. In series of insects showing peculiar 

 local colouration, species of Cerceris are included. In hot desert 

 regions the usual black ground colour tends to disappear 

 either through the extension of pale yellow markings or by the 

 substitution of a pale feriaiginous colour. This is the case to a 

 oreat extent in the neighbourhood of Karachi and to a lesser 

 degree at Quetta ; the same character also appears in Egypt 

 and Turkestan. In the wet regions of Assam and Burma the 

 black ground colour is retained, but the usual yellow markings are 

 replaced in a number of species by a dull brick red. In the 

 Shillong district species of Cerceris, Crabro, Ody?ierus, Uwnenes, 

 Gcelioxys and a saw-fly which I have not been able to identify were 

 all influenced in this manner. In Tibet at a high elevation the 

 iisual yellow markings tend to be replaced by creamy white, 

 Cerceris, Oclijn&nis, and an allied species of saw-fly being again 

 afiected. In Australia also the prevalent orange colour is shown 

 in the same genera, with the exception of the saw-fly, and also in 

 other genera of JEumenidce , more rarely in species of Spliecoidea 

 of other genera. But in all countries the extent of the colour 

 in Cerceris is subject to much local variation, and any key to the 

 species in which colour is used extensively must be unsatisfactory. 

 I have therefore based my key on that given by Schletterer for 

 the Palsearctic species of the group, in which structural characters 

 are used as the basis, and have also thought it well to add several 

 plates, which will explain the shape of the clypeus and pygidial 

 area in difierent species better than can be done in words. 



My thanks are due to Colonel Nurse, Mr. Comber and Mr. 0, S. 

 Wickwar for the supply of specimens for this paper. I have also 

 been able to make use of the Rothney collection, now in the 

 Oxford museum, containing many of Cameron's types, through 

 the kindness of Professor Poulton ; and also the National Collec- 

 tion at South Kensington, which contains Smith's and Bingham's 

 types. Mr. Bainbrigge Fletcher has also sent the collection of the 

 oenus from the Pusa collection to me for examination. 



I have not described species from the male sex, considering that 

 as a rule it is inadvisable in this genus to make the male the type 

 of a new species. In my key to the males it should be remembered 



