LAMPYRIDAE. 189 



Last joint of maxillary palpi dilated, and securiform ; 

 Hind angles of thorax rounded ; 

 Head moderately long ; 



Front broadly rounded at tip ; claws cleft. Rhagonycha. 



Front emarginate at tip ; claws toothed, rarely cleft. Telephokcs. 



Head short and broad ; claws not cleft. Polemics. 



Hind angles of thorax incised ; head short and broad. Silis. 



Last joint of maxillary palpi suboval, obliquely truncate ; 



Sides of thorax biincised ; antenna} strongly serrate. Ditemnus. 



The type and only species of Ditemnus is Silis lepida Lee. ; 

 the female is unknown. The hind angles of the thorax in the 

 male are deeply incised ; the posterior portion forms a long obtuse 

 process ; the anterior portion a long spine, in front of this the 

 sides are emarginate, and the anterior angles are prominent later- 

 ally and rounded. 



Group IV.— Malthini. 



The head is moderately short, frequently large and strongly 

 narrowed behind the eyes ; the gular sutures coalesce on the 

 median line ; the anterior margin of the thorax is broadly rounded. 

 The elytra are much shorter than the abdomen, and the wings are 

 exposed and folded along the dorsal surface of the abdomen. The 

 mandibles are shorter and stouter than in the preceding groups, 

 and are toothed in some genera, simple in others. The tarsi are 

 not spongy pubescent beneath, and the first joints are compressed. 



Maxillary palpi with the last joint triangular; 



Mandibles strongly toothed ; claws with broad tooth, contiguous at base. 



Tkypherus. 

 Mandibles ; claws small, acute, not toothed. Lobetus. 



Maxillary palpi with the last joint oval pointed ; 



Antenna? strongly serrate. Tytthonyx. 



Antennae filiform, distant from the eyes ; mandibles toothed. 



Malthinus. 

 Antenna? filiform, very near the eyes ; mandibles simple. Malthodes. 



Lacordaire describes the mandibles of Trypherus as slender 

 and simple. It is very difficult in these insects to see the form 

 of the mandibles without dissection, and I find, in the present 

 case, that they are stouter than usual in this family, and armed 

 near the tip with a strong tooth. Renewed observations will 

 therefore be necessary to establish the difference between Try- 

 pherus and the East Indian genus, Ichthyurus Wedwood. 



