AMERICAN COLEOPTERA. 121 



Jiotesfin the Species of RHIPIPHORUS of the 

 United States. 



BY GEORGE H. HORJ^, M. D. 



The following essay is tlie result of a study made necessary by 

 an attempt to name specimens which have been from time to time 

 sent me. 



The males have the antennae bipectinate or flabellate ; vertex in 

 front less convex and above more truncate than in the females; an- 

 terior tarsi feebly dilated, pubescent in most species, spinulose in two 

 only. The form of the vertex and punctuation of the head have no 

 specific value, while color has, if possible, still less. The prolongation 

 of the maxillary lobes seems not to have generic value, specimens of 

 Macrosiagon are before me in which the lobes are not at all visible 

 while in Rhip. Umhatus they are as long as in 31. dhnidiatus and 

 the near association of these two species would certainly be very 

 unnatural. 



There are certain structural characters of great value which point 

 out an arrangement of the species much more natural than any here- 

 tofore proposed, and when reduced to a tabular form the recognition 

 of our species is made more certain. 



In most of the species the prosteruum is very slightly 'prolono-ed 

 and the coxae are contiguous in their entire length. In Umbatus and 

 linearis the prosternum is prolonged into a slender process whicli is 

 nearly as long as the coxae and which separates them in nearly their 

 entire length. 



Ih many species the second joint of the hind tarsus is much shorter 

 than the third and flattened and rather broad above. In crueutus alone 

 the second joint is longer than the third. 



The following table will enable our species to be known. 



Anterior coxae contiguous in their entire extent. 

 Anterior tarsi % spinulose beneath; elytra very acute. 



Basal lobe of thorax with a strong elevation; second joint of hind tarsi 



not flattened above flavipeililis. 



Basal lobe of thorax transversely notched at tip; second joint of hind 



tarsi flattened above (Iiiili<liatiis. 



Anterior tarsi % with three joints pubescent beneath. 



Second joint of hind tarsi shorter than third and flat above. 



Thoracic lobe with obtuse elevation and a deep fovea on each side. 



bifoveatiis. 



TRANS. AMER. ENT. SOC. (16) SEPTEMBER, lS7o. 



