﻿MELOLONTHID^E OF THE UNITED STATES. 233 



scales. Pectus densely clothed with long yellowish hair. Femora and inner margin 

 of the posterior tibiae fringed with long hair. 



3. RHIZOTROGI. 



These are distinguished among the other Melolonthidae with transverse not promi- 

 nent anterior coxae, by the deeply emarginate labrum, the anteriorly margined thorax 

 without apical membrane, the narrow parapleurae, and the connate ventral segments. 

 Specimens, and perhaps even species occur in which this last character is not very 

 obvious. 



Additional characters, not previously noticed are : the 5th ventral segment is joined 

 with the propygidium by an angulated suture, which is sometimes partly obliterated, 

 the stigma is placed upon the suture at the angle, and nearer the posterior than the 

 anterior margin. 



The last joint of the maxillary palpi is frequently impressed and sometimes deeply 

 excavated, the ungues and mandibles seem to vary in form within the same genus. 

 In the native genera the posterior coxae are entirely corneous, without any posterior 

 membranous margin : the posterior external angle is sometimes produced ; the antennae 

 are 9 or 10-jointed, with the club three-jointed. 



Our genera may be thus arranged : 



Unguiculi haud serrati, prope medium dentati j 

 Ligula profunde emarginata j 



Antennae lO-articulatse ......... Eugastra Lee. 



Antennae 9-articulatae . . . . . . • . . Endrosa Lee. 



Ligula fere truncata ; 



Labrum bilobum .......... Lachnosterna Hope. 



Labrum concavum, haud bilobum ....... Gynnis Lee. 



Unguiculi plus minusve serrati, nonnunquam ad medium dentati ; ligula fere truncata Listrochelus Blanch. 



Eugastra Lee. -<_ 



Corpus crassum, convexum, sexus utriusque apterum, supra et subtus glabrum. Labrum bilobum ; man- 

 dibulae prominulae, maxillae validae ad apicem dentatae. Ligula parum concava, antice profunde subquad- 

 ratim emarginata. Palpi maxillares articulo ultimo elongato, levissime obovali, labiales articulo ultimo 

 ovali. Antennae 10-articulatse, articulis 3 — 6 subaequalibus, 7mo breviore, haud latiore ; clava sexus utrius- 

 que parva triphylla. Tibiae posteriores coronatae, tarsi tibiis paulo longiores, setosi, postici articulo lmo vix 

 breviore 5 unguiculis dente acuto prope basin armatis ; calcaribus posticis sexus utriusque liberis. Abdomen 

 segmento ventrali ultimo feminaa prominulo, maris brevi ; penultiino maris asquali, feminae transversim 

 impresso. 



This genus represents on this continent the apterous Rhizotrogi of the group Geo- 

 trogus, but differs from that genus by many characters. The deep emargination of 

 the ligula is bisinuous but almost square at base, and will readily distinguish this 



from all the other genera of the tribe. 



60 1 



