92 MANDIBULATA. — COLEOPTERA, 



four last genera, it is at once known by the posterior monodactyle 

 tarsi ; although, in Acilius, one claw is exceedingly minute. 



| Sp. 1. Roeselii. Olivaceo-niger, clypeo thoracis elytrorumque margine ex- 

 terioriJlavis 9 elytris obsolete striatis. (Long. corp. 1 unc. 1 lin.) 



Dy. Roeselii. Fabricius. — Cy. Roeselii. Curtis, iv. pi. 151. Steph. Catal. p. 53. 

 No. 532. 



Olive-black, rather glossy: head with theclypeus and anterior margin ochraceous- 

 yellow : thorax with a faint dorsal channel, the base obsoletely strigose ; the 

 lateral margin ochraceous : elytra a little convex, with three longitudinal striae 

 of very remote impressed dots, the outer margin with a yellow or ochraceous 

 streak, reaching from the base nearly to the apex, the margin itself olivaceous : 

 body testaceous or ferruginous beneath : legs testaceous, the anterior palest ; 

 the posterior with the tibiae and tarsi pitchy. Female with the thorax thickly 

 covered with irregularly-waved strigae ; and the elytra with about five-sixths 

 of the surface from the base with abbreviated, frequently anastomozing, lon- 

 gitudinal striae; the anterior tarsi simple: in other respects similar to the 

 male. 



Roesel having described the metamorphosis of this species, Fabricius, in com- 

 memoration thereof, named it after him. 



The only indigenous specimen 1 have seen of this fine insect is 

 a female, which was taken at the end of September, 1826, at 

 Walton, in Essex: it is in the collection of J. H. Gricsbach, Esq., 

 who informed me, some time since, that a second example had 

 occurred. 



Genus LXXXIX. — Acilius, Leach. 



Palpi, external maxillary with the second joint shorter than the third, the ter- 

 minal longer than the latter ; swollen in the middle, attenuated and rounded 

 at the apex : labrum very slightly emarginate : mandibles bifid at the apex : 

 mentum transverse, scarcely emarginate anteriorly. Antennae with the first 

 and third joints nearly equal in length, the second short: head small, rounded: 

 scutellum distinct : elytra ovate, smooth, sulcate and hairy in the females : 

 legs natatorial; tibiae short: tarsi five-jointed; posterior didactyle, the inner 

 claw very minute : anterior tarsi patelliform in the males ; intermediate simple 

 in both sexes. 



The fusiform terminal joint of the external maxillary palpi, 

 and the superiority of its length over the penultimate, and the dif- 

 ferent form of the mentum, well distinguish this genus from all the 

 preceding : the females have the elytra sulcated, the sulci thickly 

 clothed with hair; and the males the anterior tarsi alone dilated. 



