THE CANADIAN ENTOMOLOGIST. 30*? 



On comparing these at home with the larvae of the Meadow Rue 

 Borer, I found that while they resembled each other very closely, they 

 were still easily distinguished by the following points : 



In the Meadow Rue Borer the cervical shield is brown, though lighter 

 than the head, while in Onusta it is almost of the same colour as the body. 

 The anal plate is smaller than in Onusta, and is brown, while in Onusta 

 it is pale yellowish. The warts are also more prominent in the Rue Borer, 

 especially on the 8th abdominal segment. 



As this species is unquestionably distinct from Cerussata, I describe 

 it as follows, naming it after its food- plant : 



Gortyna Thaliclri, n. sp. — (The Meadow Rue Borer.) 



AlaV expanse, 34-40 mm. Very similar to Cerussata, but less 

 brightly coloured. It is also a smaller species, and though size does not 

 count for much in this group, there being dwarfs and giants in all the 

 species, the average size is of some assistance in separating the forms. 

 Primaries of a warm brown, with a slight purplish tinge within the t. a. 

 line and beyond the t. p. line, or what Dr. .Strecker designated the basal 

 and limbal areas. Markings similar to those of Cerussata, but the t. a_ 

 line is generally a little more distinct, from the fact that the yellowish 

 costal mark where it starts is generally better defined, and the line is more 

 bordered with yellowish. The orbicular is rounder than in Cerussata, 

 and generally has a brown spot in it towards the apex of the wing, which 

 frequently reaches the edge, and so gives the spot the shape of a round- 

 ended crescent. 



The t. a. and t. p. lines are as nearly as possible alike in both species, 

 but the median shade, which, however, varies considerably as to position 

 in both species, in generally nearer the t. p. line in Thalidri than in 

 Cerussata. 



In Cerussata there is generally a bright, almost red, patch in the 

 central area of the primaries extending forward from the inner margin to 

 about half way between veins ib and ic of the diagram on page 16 of Dr. 

 Holland's Moth Book, which Thalidri does not have, though occasionally 

 that portion of the wing is a little brighter in colour than the rest. 



But the chief distinction between the moths is in the reniform, which 

 in Cerussata is, as stated by Grote,* slightly oblique, the angles which it 



*This species is erroneously attribu'ed by Dyar to Grote and Robinson, and in this 

 error is followed by .Smith in his check List of 1903, though correctly referred by him 

 in his first check List of 1891. 



