58 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 65. 



them by the transverse ridge on the caudal part of the frons and its 

 connection with the ridge on the caudal part of the vertex, the 

 length of the segments of the maxillary palpus, the shape of the 

 labium, the length of the segments of the labial palpus, and by the 

 hooks on the fifth abdominal segment. 



TABLE TO THD SPECIES OF THE GENUS TETRACHA. 



Median hooks each with but a single stout seta ; lateral and caudal margins 



of pronotura pearly white 1 



Median hooks each with two short, stout setae; lateral and caudal margins of 



pronotum brown euphratica, p. 58. 



1. Diameter of ocellus 2 slightly greater than the distance between ocelli 1 and 

 2 ; pronotum less than four millimeters in width, color of pronotum a dark 

 purple; secondary setae on abdomen not numerous and found only on the 



chitinized areas Carolina, p. 59. 



Diameter of ocellus 2 slightly less than the distance between ocelli 1 and 2 ; 



pronotum 4.5 mm. or more in width, color a dark purplish bronze with a 



green reflection ; secondary setae on abdomen numerous and found between 



as well as upon the chitinized areas virginica, p. 60. 



DESCRIPTION OF SPECIES. 

 TETRACHA EUPHRATICA LatrieUe and Dejean. 



Figs. 156 and 168. 



Mayet, reared, larvae deposited in the U. S. National Museum by Dr. 

 A. Boving, 



Color. — Head and pronotum a purplish bronze, head with a dis- 

 tinct blue reflection, lateral and caudal margin of pronotum dark 

 brown ; setae brown. 



Head. — Setae on dorsal aspect long and prominent; diameter of 

 ocellus 2 distinctly greater than the distance between ocelli 1 and 2 ; 

 fronto-clypeo-labral area longer than wide; transverse ridge on 

 caudal part of frons with three setae; antenna with the proximal 

 segment slightly longer than the second, the third one-half and the 

 distal slightly more than one-fourth the length of the second, the 

 proximal and second segments each with 12 to 14 setae; maxilla 

 with the proximal segment of the galea bearing 4 stout setae on 

 its mesal margin; (labium damaged so that characters could not be 

 described). 



Thorax. — Pronotum with the cephalo-lateral angles extending 

 almost as far cephalad as the mesal portion, lateral margins very 

 slightly carinate; primary setae large and prominent, secondary 

 setae small and not numerous (fig. 156). 



Abdomen. — Chitinized areas distinct, secondary setae short, fine, 

 and moderately numerous, few occurring between the chitinized areas 

 (fig. 168); median hooks with two prominent setae; inner hooks 

 slightly more than one-half the length of the median hooks, and 

 with two fine, inconspicuous setae; two prominent setae cephalad of 



