THE CLICK BEETLES. 



71!) 



(Id. Marginal line of thorax, strictly lateral, visible from above 

 throughout its full length; elytra yellow, with black crossbar; 

 length less than 5 nam. XVII. Horistonotus. 



cc. Tarsi with fourth joint lobed beneath ; length 7 mm. 



XVIII. Esthesopus. 



bh. Prosternal spine acute at apex; scutellum oval. 



e. Presternum very broad, sutures single, straight or convex on outer 

 side. 



/. Tarsal claws simple; tarsi of moderate length, clothed with stiff! 

 hairs. 



g, Prosternal sutures straight, either parallel or converging very 

 little behind the middle ; side pieces of mesothorax reaching 

 the middle coxae ; length over 5 mm. 



XIX. Cbyptohypnus. 

 gg. Prosternal sutures curved and very evidently converging be- 

 hind the middle ; side pieces of mesothorax not reaching the 

 coxae ; smaller, less than 5 mm. ; elytra usually with yellow 

 spots. XX. Hypnoidus. 



ff. Tarsal claws with a tooth at middle ; tarsi long, pubescent ; uni- 

 form piceous black. XXI. GEdostethus. 

 ee. Presternum of moderate width, sutures double, either straight or 

 concave on outer side. 

 h. One or more of the tarsal joints lobed beneath. 



i. Second joint of tarsi without lobes. 



j. Third joint alone lobed. XXII. Anchastus. 



jj. Fourth joint alone lobed. XXIII. Monocrepidius. 



ii. Second and third joints of tarsi with long lobes ; color brown ; 



length 10 or more mm. 

 k. Mesosternum horizontal ; front of head with two crests unit- 

 ing above with frontal margin. XXIV. Dicrepidius. 

 kk. Mesosternum oblique ; front of head not crested. 



XXV. ISCHIODONTUS. 



hh. Tarsal joints not lobed beneath. 



I. Prosternal sutures excavated in front; joints 1 to 4 of tarsi 



gradually increasing in length, ciliate beneath ; color usually 

 variegated. XXVI. Elater. 



II. Prosternal sutures not excavated in front. 

 m. Third joint of antennae longer than second. 



XXVII. Drasterius. 

 mm. Second and third joints of antennae small, equal. 



Megapenthes. 



i. Margin of the front not elevated behind the labrum ; size larger, 15 or 

 more mm. in length. 

 n. Sides of mesosternal cavity sloping downward, not prominent; ely- 

 tra black. XXVIII. Ludius. 

 nn. Sides of mesosternal cavity protuberant, prominent; color brown. 



XXIX. Orthostethus. 



[46—23402] 



