No. 2323. LARVAE OF THE CLERIDAE—BOVING AND CHAMPLAIN. 581 



in front and the lateral notch behind is horizontal and straight, it 

 separates deeply the epipleural and hypopleural areas. 



Areas. — The prothoracic tergal region {Prtg) is siibsellate with 

 transverse straight front margin, with rounded, posteriorly oblique 

 side margin which ends at the dorsal notch and with transverse, short 

 hind margin above the dorsal notch. The median area of epipleurum 

 is incorporated in tergum or possibly replaced by a lowering of 

 tergnm. With exception of a narrow lateral margin the whole tergal 

 region is covered by the tergal shield. In most genera, this shield is 

 somewhat broader than the head and only in a few genera, as 

 Thaneroclerus, of the same size. The preepipleurum (^e) is small, 

 and no preepipleural arm is developed in prothorax. The Postepi- 

 pleurum {poe) is triangular and well developed. The Hypopleurum 

 has usually Pre- and Posthypopleural chitinizations {ph and poh).^ 

 These are separated by a short, vertical Hypopleural Suture {hs) 

 above a little, ventrally extending hypopleural arm, which carries an 

 articulating fossa for the coxal condyle. The Presternal Area {pst) 

 is distinctly developed in the cervical membrane and conspicuously 

 marked by a pair of subtriangular or rounded presternal plates, one 

 on each side of the middle line. The Preeusternum {pres), a sternal 

 area in front of the prehypopleural chitinization, and the Eusternum 

 (es), behind this structure, arc fused and often medianly covered 

 with a common, unpaired Sternal Plate {stp). The form of this 

 plate varies according to genera or groups of genera and is of distinct 

 systematic value ; narrow and lanceolate in Enoclerus and genera re- 

 lated to Enoclents, broad and pyriform in Chariessa and genera of 

 this type, and subquadrate in a genus as Monophylla. The lateral 

 arms of Eusternum are not chitinized. The Sternellum * is not pres- 

 ent as a distinct area ; its median part or Mediosternellum is possibly 

 fused with eusternum and each lateral part or Laterosternellum is 

 possibly fused with the large lobe around coxa. The Posternellum 



^ The terms Pre and Posthypopleuiul chitinizations are used here instead of the more 

 generally used terms Epistemum and Epimeron (compare Crampton, Proc. Ent. Soc. 

 Wash., vol. 20, p. 3, 1918), because a comparison between the muscles from pre- and 

 posthypopleurum in Coleopterous larvae with those from episternum and epimeron in the 

 Coleopterous adults shows that these larval and adult areas are not quite homologouB. 

 We find, for instance, that all the muscles in the adults, from episternum to the leg and 

 the region near the leg, only correspond to part of the muscles which in the larvae 

 extend between prehypopleurum and the leg and the region near the leg, while the rest 

 of the prehypopleural muscles in the larvae are homologous with muscles which in the 

 adults attach to the large wing-supporting Prehasalar Plate above episternum. 



2 The Sternellum consists of a median part or Mediosternellum and a lateral part or 

 Laterosternellum on each side. Where the mediosternellum and the laterosternellum are 

 well developed as in the larvae of Carabids and Silphids, the mediosternellum forms a 

 triangular area which anteriorly is separated from the eusternum by a transverse suture 

 between the furcal pits, and laterally defined h.v oblique sutures between the furcal pits 

 and the sternal notch, while each laterosternellum is anteriorly adjacent to the lobe 

 carrying and surrounding coxa, and laterally and internally adjacent to mediosternellum 

 and posteriorly limited by the suture between the lateral notch and sternal notch. 



