196 INTRODUCTION TO ZOOLOGY. 



DO— Middle coxal cavities closed by the sterna. 

 P— Prosternum not prolonged behind. 



(Mycetophagidae.) 

 PP— Prosternum prolonged behind, meeting the 

 mesosternum. 

 Q— Anterior coxal cavities open behind. 



(Cryptophagidae.) 

 QQ— Anterior coxal cavities closed behind. 



(Erotylidse.) 

 LdL— Posterior coxae sulcate to receive the thighs. 



(Throscidae.) 

 KK— Anterior coxae transverse. 

 L— Posterior coxae flat, not sulcate to receive the thighs. 

 M— Antenna straight. 

 N— Tarsi more or less dilated, first joint not short. 



(NltldulidsB.) 



NN— Tarsi slender, first joint short (Trogositidae.) 



MM— Antenuse geniculate ; tibiae usually all dilated. 



(Histeridae. ) 

 LL— Posterior coxffi grooved for the reception of the thighs ; 



body oval, convex, legs retractile (Byrrhldffi.) 



GG— Tarsi four-jointed. 



H— Wings fringed with hairs; very small species (Corylophidae.) 



HH— Wings not fringed with hairs. 

 I— Ventral segments 1-4 connate. 



J— Antennae regular; legs not fossorial (Colydiid^.) 



JiT-Autennae short, ii-regular; legs tossorial.... (Heteroceridae.) 

 II— Ventral segments free. 



J~ Anterior coxas transverse (Nitidulidffi. ) 



JJ— Anterior coxiB globose. 



K— Tarsi slender (Endomychidae.) 



KK— Tarsi more or less dilated and spongy beneath. 



(Erotylidae.) 

 J JJ— Anterior coxae oval. 



K— Form depressed ; head, free (Mycetophagidae. ) 



KK — Body cylindrical, thorax prolonged over the head. 



(Ciidae.) 

 QGG— Tarsi 3-jointed. 

 H— Wings fringed with long hairs; abdomen with 6 or 7 ventral 

 segments ; autennEe slender, verticillate, minute species. 



(Trichopterygidae.) 

 HH— Wings not fringed. 

 1— Tarsi with the second joint dilated, 

 J— Claws appendiculate or toothed ; first ventral segment with 



coxal lines (Coccinellidae.) 



JJ— Claws simple ; first ventral segment without coxal lines. 



(Endomychidae. ) 

 II— Tarsi with second joint not dilated. 

 J— Elytra entire; ventral segments nearly equal. (LathrldiidEE.) 

 JJ— Elytra truncate; ventral segments 1 and 5 longer. 



(Trogositldse.) 

 EE— AnteunsE serrate. 

 F— First and second ventral segments connate; tarsi with membra- 

 nous lobes ...(Buprestidas.) 



FF— Ventral segments free. - 



G— Tarsi 4-jolnted (Ciidae.) 



GG— Tarsi 5-jointed. 

 H— First ventral segment elongated; antenniE terminated by a 



two-jointed club (Pcinidffi.) 



HH— First ventral segment not elongated, 

 I— Hind coxaa sulcate to receive the thighs. 

 J— Prontcoxaa globose. 

 K— Prothorax loosely articulated ; prosternum prolonged be- 

 hind ; front coxal cavities entirely prosternal. 



(ElaterldiP.) 



KK— Prothorax firmly articulated; front coxal cavities 



closed behind by mesosternum; antonnie sometimes 



with a 3-jointed club (Throscida3.) 



