33 



The sternal border (Text fig. 4, 67>. s.) is in contact 

 with the sternum, and forms the ventral boundary of the 

 endosternite. 



The articular border (Ab. .s.) passes upwards and out- 

 wards, and is equal in length to the sternal border. It is 

 connected with the arthrodial membrane in contact 

 with the coxopodites of the fourth and fifth thoracic 

 appendages. 



ernum. 



FIG. 4. Diagram of a typical arthrophragm. 



Db.p. = dorsal border of the endopleurite. 



Db.s. = dorsal border of the endosternite. 



Eb.p. = epimeral border of the endopleurite. 



Ab.p. articular border of the endopleurite. 



Ab.s. = articular border of the endosternite. 



Sb.s. = sternal border of the endosternite. 



A.F. = apodemal foramen. 



The outer border passes inwards and upwards, and at 

 its upper and lower ends fuses with the endopleurite. 

 This fusion -is interrupted in the middle region of the 

 border by the large apodemal foramen (A.F.} which lies 

 between the endosternite and endopleurite. 



The inner part of the dorsal border (Db. s.) passes 



