NORTH AMERICAN COLEOPTERA. 165 



From what has been observed in the study of our genera it is 

 evident that some of Chapuis' groups must be modified as to their 

 composition. Homophceta should certainly not remain with the 

 CEdionyches nor Fhrynocepha with Halticpe, and the two have the 

 essential characters of the Aspicelse. The Monoplati contains in 

 Chapuis thirty-nine genera ; one of these (Pachyonychis X Clk. = 

 Hamletia Cr.) has the anterior coxal cavities open behind, and is a 

 true CEdionychide, and from the fact that in our fauna a genus has 

 occurred which might readily be placed in the group by its facies 

 and with open front coxal cavities, it seems very probable that a 

 second careful examination would show that some of the genera at 

 present placed in Monoplatites should be removed. 



The entire tribe is one which presents many difficulties in its study. 

 The characters of taxonomic importance are few, and these are so 

 often interlinked as to make it almost impossible to decide to which 

 priority of impijrtance should be given. 



At this point I desire to acknowledge the kind assistance of friends 

 in the preparation of the work. 



The Museum of Comparative Zoology at Cambridge contains the 

 types of Melsheimer, Ziegler and LeConte ; these I have been per- 

 mitted to examine carefully during a recent visit to the Museum. 



The National Museum at Washington has added vastly to the 

 series examined. 



To Messrs. Ulke and Schwarz, of Washington, I am indebted for 

 the loan and gift of much valuable material not elsewhere accessible. 



To Messrs. Angell and Roberts, of New York, I owe important 

 data in distribution obtained from a loan of their material. 



To Mr. Henshaw, of Boston, and Blanchard, of Lowell, I am in- 

 debted for a knowledge of the species of the New England region. 



In this city the Wilt collection, now the property of the American 

 Entomological Society, contains the most extensive material exam- 

 ined, although a little less rich in species than the LeConte cabinet. 



From Messrs. Wenzel and Liebeck much information of value 

 has been obtained regarding the species of the vicinity of Philadelphia. 



My own cabinet needs scarcely more than half a dozen species to 

 make it complete. 



From the large material examined I have been enabled to deter- 

 mine the limits of the species from numbers of specimens, and it is 

 extremely rarely that I have ventured to indicate species on unique 

 examples, and then only when the chai-acters have been so pronounced 

 as to warrant it. 



