it necessary that the groups should be separated and formed 

 into new genera : this, however, is a difficult task, and the la- 

 bourer in the field of science must be contented in the first 

 instance to give a general outline ; the minutiae required to 

 establish satisfactory characters can only be obtained by ex- 

 tensive and repeated investigation. With such manifest ob- 

 stacles in an Order, the classification of vv^hich has been so 

 much neglected, it becomes an arduous undertaking: it is 

 therefore with considerable hesitation that the subject of the 

 present article has been constituted into the type of a new 

 genus ; and had it not been perfectly new to this country, it 

 would not at present have been laid before our readers. 



After examining 7 specimens, 3 of which were British, I 

 could discover no difference in the structure of the antennae, 

 which from their simple form indicate the female sex, although 

 the abdomens of the paler specimens, being slightly contracted 

 towards the base, at first led me to believe that these speci- 

 mens were males : if such be the case, the variety described is 

 p female. I am, however, inclined to think that the males 

 have not been detected at present, and that they will be found 

 to possess ciliated, not pectinated, antennae; in which case they 

 will associate with the following species. 



1. Geometra tetragonaria Haiso. MSS. 



For the introduction of this rare species into our Fauna we 

 are indebted to J. C. Dale, Esq., who first took it on the 

 trunk of an Oak near Brockenhurst, Hants, June 2nd, 1823; 

 a 2nd specimen upon the trunk of a Scotch Fir, Parley Heath, 

 May 11th, 1824; and a 3rd near Lyndhurst, May 31st, 1824-. 

 It has this year again appeared in the New Forest, where I 

 am informed 2 specimens were captured. 



The plant figured is Hedysarum Onohnicliis (Cock's Head, 

 or Sainfoin). 



