396 CLASSIFICATION OF THE RIITNCHOPHOROUS COLEOPTERA. 



cesterniis prolonged forwards, so as to extend along the sides of 

 the prothorax. Dorsal segments membranous, last one large, 

 corneous, divided into two in $ : ventral segments unequal, 1st, 

 and 2d very large, more closely connected, suture arcuated : 3d 

 and 4th short, sutures deep, 5th as long as the two preceding ; • 

 lateral extension moderately wide, wider behind, p3gidium artic- 

 ulating with both 4th and 5th ventrals. Legs slender, tibiae trun- 

 cate, spurs small, tarsi 4-jointed, narrow, setose beneath. ^^ "^ 

 Several species of Thecesternus are found in the interior^^^gions 

 of the continent, from Illinois to Utah, under dried buffalo excre- 

 ment, and similar objects. 



OTIORHYNCHID^. 



In a large number of genera* of Rhynchophora, at the front part 

 of the mandibles, may be seen a round or oval depression, having 

 the appearance of a scar, and which served, during the pupa stage, 

 and for the early part of the imago life, as an attachment for a 

 deciduous piece, of a conical and usually slender form. Many 

 times specimens had occurred in which one or both of these pieces 

 were still adherent, and the explanations thereof were' varied and 

 incorrect. t^The opinion of Lacordaire seems to be quite satisfac- 

 tory, that they are probably of service in enabling the insect to 

 cut its way out from the nest or cell in which the transformation 

 takes place. 



While recognizing the frequent occurrence of this singular 

 structure, altogether without parallel among other insects, it does 

 not seem to have occurred to Lacordaire, that we have here a 

 character of great importance for systematic purpose, and that 

 after removing the large mass of such genera, the normal series of 

 Curculionidse would be much more amenable to classification. In 

 fact I think it ma}" be shown that the confusion and indeliniteness 

 of the first part of the classification of Lacordaire is mainly owing 

 to the intercalation of genera with scarred mandibles and those 

 with simple mandibles. I have therefore placed the former as a 

 separate family, having the following general characters. 



The body affects two forms ; in the apterous species the elytra 

 are connate and convex with the humeri rounded ; in the winged 

 species they are more oblong, with the humeri more or less prom- 



* Lacordaire, Gen. Col. vi, 5 (note), 

 t Miiller, Germar's Mag. iii, 42i. 

 (452) 



