HEMIPTERA. 



projecting beyond the line of 

 the margins of the abdomen . . 2. 

 2. Posterior angles of the last seg- 



ment of the abdomen unarmed 3. 



B. Sternal keel not emarginate in front. 

 a. Sternal keel not produced ante- 

 riorly beyond the intermediate 

 coxae. 



1. Antennae of five joints 4. 



2. Antennae of four joints. 



a. Sternal keel emarginate be- 

 hind for the reception of a 

 ventral spine 5. 



b. Sternal keel not emarginate 

 behind 12. 



b. Sternal keel produced beyond the 

 intermediate coxae ; sometimes 

 reaching or passing the anterior 

 coxae in the form of a keel or ob- 

 tuse spine. 



1. Antennae of five joints 6. 



2. Antennae of four joints. 



a. Posterior margin of the tho- 

 rax produced over the base 

 of the scutellum. 

 * Posterior angles of the last 

 segment of the abdomen 

 produced beyond the anal 

 apparatus; produced an- 

 terior portion of the ster- 

 nal keel free. 



a. Abdomen narrowed to- 

 wards the apex ; spinous 

 portion of the sternal 



keel compressed 7. 



/3. Abdomen nearly as 

 broad at the apex as at 

 the base; spinous portion 

 of the sternal keel cylin- 

 drical, somewhat acute 

 t Posterior angles of the last 

 segment of the abdomen 

 not produced beyond the 

 posterior margin of the 



anal apparatus 9. TESSARATOMA. 



Posterior margin of the 

 thorax not produced 10. EUSTHENES. 



317 

 EDESSA. 



ACERATODES. 



BRACHYSTETHUS. 



APLOSTERNA. 

 MATTIPHUS. 



PlEZOSTERNUM. 



MUCANUM. 



8. PYGOPLATYS. 



b. 



