INTRODUCTION. 



13 



Chrysomela [Melasoma] cenea, L. Norway. Pear. 

 Chrysomela [Melasoma] cuprea, F. Europe. Willow, Poplar, 

 Aspen. 



Chrijsomela [Melasoma] lapponica, L. America. Willow. 

 Chrysomela [Melasoma] lineatopunctata, Forst. (scrvpta, F.). N. 



America. Willow, Poplar. 

 Chri/somela [Melasoma] populi, L. Europe. Willow, Poplar. 

 Chrysomela [Melasoma] tremulce, F. Europe. Wallow, Aspen. 

 Phaedoaia areata, F. (Plac/iodera circumcincta , Sahib.). Africa. 



Cotton. 



Paropsides duodecimpustulata, Gebl., var. hieroylyphica, Gebl. 



Shillong, India. Pear. 

 P hytodecta viminalis, L. Europe. Willow. 

 Phytodecta fornicatus, Briiggem. Russia. Lucerne. 

 Phnllodecta vulgatissima, L. France. Osier. 

 Pliyllodecta vitelline?, L. Europe. Salicc. 



Eatomoscelis adonidis, Pallas. America. Turnip and Virginian 

 Stock. 



In 'Indian Museum Notes,' vol. iii, no. 5, p. 44, 1894, an 

 insect identified by Jacoby as Phaedon brassicw, Baly, was recorded 

 as attacking the mustard crop at Golaghat, Assam. Subsequently 

 Jacoby appears to ha\e altered his opinion and described the 

 Golaghat insect as Ph. assamensis, Jac. ; I think he was correct in 

 regarding it as a distinct species, for I have examined the types 

 of both species in the collection of the British Museum and find 

 them different. Although there is no record of their attacking 

 the mustard crop at Golaghat on the labels of the insect named 

 Ph. assamensis in the British Museum, I do not consider it very 

 far wrong to assume that the latter are some of the actual 

 attackers of the crop at Golaghat. 



On the formation oj ey or Tables. 



The following remarks are inserted here, as the use of dicho- 

 tomous tables does not appear to have been always understood by 

 workers in India. 



A dichotomous key or table of a group of organisms is a 

 concise and comparative statement of a selection of characters 

 arranged in a certain way with the object of facilitating the 

 recognition of species rapidly and without difficulty. In designing 

 a key it is also desirable, where possible, to express relationships 

 in the group, but it is not often that the material at hand lends 

 itself to such treatment, because we are not in possession of all 

 the facts. Keys of the three kinds exemplified below, and some- 

 times several keys of any one of those kinds, may be framed for 

 the same group of organisms, all being equally serviceable. The 

 first principle in making a key should be a proper selection of 

 characters, which should be easily recognizable and yet contra- 

 dictory in nature; that is to say, the character chosen should be 

 found in one form or in a group of forms, while in the rest it 



