GENUS CRCESUS. 37 



The vertex is thick, clypeus incised, mandibles with 

 a long apical tooth, and no subapical. The inner 

 lobe of the maxilla is acutely pointed, and does not 

 reach the top of the outer ; the three basal joints are 

 thicker than the others, the second is nearly double 

 the length of first, the third is the longest, fourth a 

 little shorter than fifth, which is also a little longer 

 than the sixth ; the two middle joints of the labial 

 palpi are the longest, the fourth is a very little longer 

 than the first. 



In coloration the species are very similar, the head 

 and thorax being black, the abdomen black, broadly 

 banded with red ; the legs black, red, and white. 



The larvas have cylindrical bodies, and are provided 

 on the ventral surface with large glands which they 

 can protrude at will, and from which a nauseous odour 

 is given out. They feed along the edge of the leaf 

 and expose the glands by turning the abdomen over 

 the head. 



The peculiar structure of the posterior legs distin- 

 guish Croesus from Nematus proper, from which it does 

 not differ otherwise. The ventral glands of the larvae 

 are much more developed than in any species of 

 Nematus. There are four European species, and two 

 are known from North America. The genus would 

 seem to be northern in its distribution. 



Synopsis of Species. 



1 (4) Fore wings more or less clouded ; ? femora beneath or above 



black. 



2 (3) Fore wings distinctly clouded from stigma to apex; femora 



black beneath ; $ antennae black, apex of abdomen black. 



Septentrionalis. 



3 (2) Fore wings with only a faint cloud below the stigma, posterior 



femora reddish beneath ; antenna brown beneath at the 

 apex ; apex of abdomen entirely brownish-red. Latipes. 



4 (1) Fore wings unclouded; femora reddish above and beneath, 



black at apex ; J unknown. Varus. 



