248 CALIFORNIA ACADEMY OF SCIENCES. 



Thorax entirely dark; erect hairs nearly or quite wanting. 

 Entirely dark blue-green; antenna strongly serrate; size 



large (4-4.75 mm.) M. inornatus. 



Dull black, sutural tips yellow, antennae feebly serrate; 



size small (2.5 mm.) M. pristinus. 



Tips of elytra spiniform in the male, the appendix not visible 



from above M . acutipennis. 



Antennae pectinate in the male. 



Elytra appendiculate in the male. 



Appendices not visible from above M. spinipennis. 



Appendices visible from above. 



Elytra of male either entirely yellow or tipped with pale 

 rufous; appendix slender; hind tibiae yellowish testa- 

 ceous M. mirandus. 



Elytra of male entirely blue, appendix long but not very 



slender; legs blue-black M. thevenetii. 



Smaller, surface lustre greenish; appendix broad, rounded at 



tip M. directus. 



Elytra not appendiculate in the male. 



Prothorax wider than long, antennae (male) shorter than the body. 

 Elytra bluish with broad oblique pale vitta from humerus to 



sutural angle M . macer.- 



Elytra bluish tipped with yellow in both sexes. . . . M. mixtus. 

 Elytra entirely black, sides of thorax broadly reddish yellow; 



form rather stout M. ulkd. 



Elytra black with slight greenish lustre, tipped with yellow 

 in both sexes; thorax with sides very narrowly pale; 



form slender M . montanus. 



Almost entirely black without metallic lustre; form slender. 



M. nigrinus. 



Prothorax longer than wide, antennae (male) fully as long as the 

 entire body M . prolixicornis. 



62. Listrus definitus, sp. nov. 



Slender, parallel; black, shining; pubescence black and cinereous; the 

 black hairs forming a rather wide median thoracic vitta, which is a little 

 dilated posteriorly; at the apical third of the elytra is a wide transverse 

 fascia, which is a little prolonged anteriorly along the suture; and between 

 the fascia and the base is a longitudinal series of three spots on each 

 elytron, with occasionally faint indications of one or two smaller spots near 

 the fascia. Head rather sparsely punctate; antennae reaching (female) or 

 slightly passing (male) the hind margin of the prothorax, joints two to 

 five pale, all the joints longer than wide. Prothorax very slightly longer 



