PTINIDAE. 221 



Head retractile, frequently protected hy the protliorax; 

 oral organs usually small; epistonia sometimes distinct; 

 labrum distinct in all of our genera. 



Prothorax with the side pieces not separate; lateral mar- 

 gin none in the first tribe, distinct in the second ; coxal 

 cavities rounded, open behind. 



Mesosternuin small, oblique; side pieces not attaining the 

 coxtc. 



Metasternum moderate or long, side pieces narrow. 



Elytra entire; epipleurce distinct, sometimes very broad. 



Abdomen with five ventral segments, the first not elon- 

 gated, except in Lyctinre. 



Anterior and middle coxre cylindrical or snbgloV)Ose, 

 moderately or but slightly prominent, without trochantins; 

 posterior coxse transverse, not prominent or dilated inter- 

 nally in the first; sulcate behind for the reception of the 

 thighs in the second; slightly prominent internally in the 

 third and fourth subfamilies. 



Legs contractile in the second sub-family, frequently long; 

 trochanters in the axis of the thighs; tibiae slender, with 

 the terminal spurs sometimes small, sometimes large; tarsi 

 5-jointed, but with the first joint small in the third and 

 fourth sub-families. 



A family containing species, mostly of small size, which live on 

 vegetahle matters in an incipient stage of decay; many are there- 

 fore found about houses, and have been transported by connnerce 

 over the whole globe. The form varies greatly according to the 

 sub-family. 



Four sub-families are indicated as follows: — 

 Antennae inserted upon the front. Ptinin.^. 



Antenn.'B inserted before tlie eyes ; 



Tibiae without spurs. Anobiin^ij. 



Tihix' with distinct sjiurs ; 



First ventral segment scarcely longer. Bostkicuin-TJ. 



First ventral segment elongated. Lyctik.*:. 



Su])-Family I._PTININ.^. 



These insects arc of small size, with the head and thorax com- 

 paratively small. The uiitennic are inserted upon tlie front, long, 

 not serrate, and ratiier stout. The legs are long, not contractile, 

 with the trochanters larg(!; the tibia) have the spurs obsolete; in 

 the first tribe the first joint of the tarsi is not shorter than the 



