208 COLEOPTERA OF NORTH AMERICA. 



Intermediate joints of antennae longer than the first and second ; 

 Tarsi as long as the tibiae, 2d joint elongated ; 



Front margined at least at the sides. Bostrtchus. 



Front not margined at the sides. Ampuicerus. 

 Tarsi short, 2d joint not elongated ; 



Joints S and 9 of antennae transverse, rounded. Dinoderus. 



Joints 8 and 9 of antennse triangular. Ruizopertha. 



The only species known of the last genus, Bhizopertha pusilla, 

 has been introduced in specimens of wheat distributed from the 

 Patent Office. To Amphicerus belong Apate bicaudata Say, A. 

 aspericollis Germ., and Bostrichus pwictiptennis Lee. 



Tribe III.— PSOIIVI. 



The insects composing this tribe are of large or moderate size ; 

 the thorax is oval, not margined at the sides, truncate in front, 

 not protecting the head, which is large and prominent. The club 

 of the antennae is 3-jointed. The anterior coxa? are separated by 

 the prosternum. 



Our genera are two in number, and are represented only in 

 maritime California. 



Antennae 11-jointed. Polycaon. 



Antennae 10-jointed. Acrepis. 



Polycaon Lap. has for synonyms Exops Curtis, and Allceoc- 

 nemis Lee. The original unique specimen of Acrepis metadata 

 Lee. has been lost at sea, and I cannot now determine the differ- 

 ence between the genus and Psoa. It is quite possible that it 

 should be united either with Psoa or Exopsoides. 



Sub-Family IY.— LYCTIDAE. 



The head is prominent, somewhat narrowed behind the eyes, 

 not covered by the prothorax, which is trapezoidal in form, and 

 has a fine lateral margin. The antennas are 11-jointed, and the 

 club is rounded, and consists of but two joints ; the epistoma is 

 separated from the front by an indistinct suture. The anterior 

 coxae are entirely inclosed and separated by the prosternum ; 

 the middle ones are also moderately separated, and the hind coxa? 

 are widely distant ; the first ventral segment is much longer than 

 the others. 



