18 

 central elytral, lateral elytral, and apical elytral. When 



the scutellar and humeral spots are connected, they make up 



the basal elytral band. When the central and lateral 



elytral spots are connected, they make up the central 



elytral band. 



Head 



The dorsal surface of the head has relatively few 

 useful characters. On each side of the vertex following 

 the margin of the eye is a line or shallow groove, the 

 ocular stria (Fig. 1) . Its length appears to be useful at 

 generic levels and is commented upon for future reference. 

 Since this line is shorter than the eye length in the vast 

 majority of Ischyrus, its length is given as a decimal that 

 indicates how far forward the line reaches on the eye. For 

 example, it could reach "0.75 distance to the anterior 

 angle of the eye," which means the line stops 3/4 of the 

 distance from the base to the anterior angle of the eye. 

 In Figure la, the ocular stria stops at the anterior angle. 



The head size vs. eye size is given as a proportion: 

 head width between eyes = "N" eye widths (Fig. 5) . The 

 smaller the eyes or the wider the head, the larger the 

 number "N" . 



The base of the head often has structures which have 

 been called stridulatory files (Alexander et al . 1963/ 

 Arrow 1924, 1925, 1942; Delkeskamp 1959) . These structures 

 appear as iridescent spots under a dissecting microscope. 

 Study with the scanning electron microscope shows them to 



