2 /. L. LeConte on Rhynchophorous Coleoptera. 



Commencing with those Curculionidge (Adelognathi Lacordaire,) 

 in which the mentum fills the gular emargination, as in the 

 higher Tenebrionid^, we find a gradual lessening in size of the 

 mentum, itself becoming supported upon a broad, short, gular 

 peduncle, permitting the maxillae to become visible, (Phanerog- 

 nathi, Cohort 1, Lacordaire) : next the gular peduncle becomes 

 elongated, and bilobed, receiving the mentum, now reduced to 

 very small size, between its lobes (Phanerognathi, Cohort 11, 

 and also Brenthidae, and Anthribidse). 



Having in the continuance of my work on the Classification 

 of Coleoptera of North America, recently commenced a critical 

 study of our Rhynchophora, I became aware of the impossibil- 

 ity of intercalating them between the Heteromera and Subpen- 

 tamera, and am now convinced that they represent a special type, 

 which must be isolated from all other types of Coleoptera, pos- 

 sessing a systematic value equal to all the others combined. 



In seeking for the characters which should define this type, I 

 observed a remarkable diSerence in the arrangement of the 

 pieces of the under surface of the prothorax, heretofore over- 

 looked, and so far as I know, confined to this particular type. 



In other Coleoptera, the prosternum is either extended behind 

 the anterior coxse, so as to form part of the hind margin of the 

 segment, thus coming in contact with the mesosternum, or it is 

 cut off between the cox£e, and in this case (as in many others) 

 the coxal cavities are open behind : in the few exceptions 

 (Derodontus, Dacoderus) in which the coxse are contiguous and 

 the cavities closed behind, the prosternum still extends behind 

 the coxae, to the hind margin of the segment, as is shown by the 

 short sutures separating the epimera from the medial piece of 

 the prosternum. 



I have represented these modifications of form in the adjoin- 



ing wood-cuts. Fig. 1, under surface of prothorax of a Carabide 

 (Pasimachus) ; the coxal cavities are closed, and the epimera an'i 



