14 



is Engis heros of Say, whose description is very accurate. 

 These are probably the largest of the genus. 



Having now endeavored to atone for my past omission, I 

 take up your last letter. Cetonia harhata does not agree with 

 Olivier's description and figure of Trichius Inda Fabr., and 

 although I have made the comparison, not having the volume 

 at hand, I cannot point out the pecuHarities of the two species, 

 but think they differ most in the form of the thorax. 



The brief description and slight sketch of a species which 

 you think may probably belong to the genus Trichius^ has con- 

 siderably interested me, and at the same time has led me 

 to beHeve that it belongs to none of Latreille's new genera, 

 separated from Mehlontha Fabr., and more closely alhed to 

 Trichius. No species I have ever seen agrees with your de- 

 scription, nor indeed did I know that any species of the genera 

 in question were 'natives of this country. The genera to which 

 I allude are Glaphi/rus, Ampliicoma and Anisonyx. An exam- 

 ination of the nails, with a description of the genera, will prob- 

 ably determine your doubts. 



Although I have already taxed your patience so long about 

 examination of the nails, permit me to make another remark 

 now brought to my recollection ; viz., there is an extremely 

 natural section of the genus Elater^ distinguished by having 

 pectinated nails, and also easily recognized by the broadness of 

 the thorax and elytra at base, and the attenuation of the elytra 

 behind. This character has not, to my knowledge, been de- 

 scribed by any entomological writer ; the section or subgenus, 

 has perhaps as much claim to be considered a distinct genus as 

 Lebia Latr. and Bonelli (a genus separated from Cardbus)^ 

 which is also distinguished by pectinated nails. 



In the Boston Collection I find your Ghremastoclieilus piger., 

 and Dr. Pickering possesses the other, which he obtained on 

 Lynn beach. The dimensions of these insects vary. Will you 

 send me accurate measurements of the largest and smallest 

 of each of your species ; I should be glad to know them. 



