488 COLEOPTERA OF NORTH AMEUICA. 



the tarsi are not dilated nor spongy beneath, and the club of the 

 antennae is pubescent and sensitive only near the tip. 



These characters indicate relationships in various directions, 

 such as the Byrsopidse and Cossonidie, but the insect preserves 

 unchanged all the essential characters of the Cryptorhynch tyi)e 

 of CurculionidaB. 



Acamptus rigidus, from the Southern and Western States, is 

 the only representative. 



Group III. — Cryptorhyiichi. 



In this group the pectoral groove is distinctly limited behind. 

 The other characters are variable, though the front coxa? are 

 never contiguous as in some Ithypori ; a slight appearance of an 

 epipleural fold e.vists in many species. The claws are toothed in 

 Phyrdenus, but simple, and generally small in the other genera. 



The genera in our fauna are not numerous, but present several 

 categories indicating sub-groups, which it is unnecessary to define 

 at present, as their number would be increased by a careful study 

 of exotic forms. Micromastus might be placed with equal pro- 

 priety in Ithypori, near Arthrostenus, but for the present we 

 prefer associating it with Acalles : the only specimen in our 

 collection is much broken. 



Metathoracic epimera indistinct. 2, 



Metatlioracic epimera distinct. V. 



2. Metasternum very short, liumeri ronnded. 3. 

 Metasternum as long as first ventral segment. 6. 



3. Clnb of antennte annulated. 4. 

 Club of antennae solid. Eurhoptus. 



4. First and second ventral connate, suture distinct, deeply impressed ; 



eyes coarsely granulated. f*. 



Suture between first and second ventral obliterated ; tliird and fourth 

 very short ; prothorax prolonged over the head ; eyes finely granu- 

 lated, nearly covered in repose. Lembodes. 



5. First and second ventrals longer. Micromastus. 

 First ventral longer, 2—4 equal; claws very small, approximate. 



Acalles. 



6. First ventral longer, 2-4 short, equal ; claws slender, divergent, rarely 



approximate. • Pseudomus. 



7. Tibiffi slender, more or less sinuate. 8. 

 Tibiae strongly compressed. 11. 



8. Mesosternum deeply emarginate. 9. 

 Mesosternum feebly emarginate. Tyloderma. 



