578 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 57. 



clerus, slightly concave in most of the genera, and conspicuously 

 incurved and oblique in Trichodes and Priocera. The dorsal and 

 ventral faces of epicranium are smooth or slightly sculptured in all 

 forms, with one exception, Enoelerus sphegeus., where a large tubercle 

 is developed dorsally on each epicranial half near the posterior end 

 of the frontal sutures. 



The Ocelli {oc) are located on epicranium behind the ventrolateral 

 part of the antennal ring. They are usually of moderate size but 

 projecting so much that they can be traced on the cast skins. Their 

 number vary according to genera or groups of genera, with five in 

 the plurality of the forms, four in Tarsostenus., three in Cymatodera.^ 

 two in Necrohia^ one in Monophylla and Priocera^ and no distinctly 

 marked ocellus in Orthoplenra. 



The Clypeus (<?) is well developed, trapezoidal, without setae; in 

 several forms rather indistinctly^ in others distinctly separated from 

 frons. 



The Lfabrum {I) is Avell developed, movable, subrectangular, with 

 rounded corners; its anterior margin may be slightly convex as in 

 Monophylla,, straight as in Cymatodera or slightly sinuate as in 

 Enoclerus ; a series of setae are placed along the anterior margin and 

 a few on the disk within the margin. 



The Antenna (a), projecting from an antennal ring, exceeds the 

 anterior margin of the labrum, in all forms except Hydnocera,, where 

 it reaches that margin; the articulating basal membrane (6m) is 

 large, in some forms joint-like, extended. The basal joint (/) is 

 large in most of the genera, from two to four times as long as the 

 second joint (//) ; only in Orthopleura and Pnoccra short, in 

 the former genus as long as the second joint, in the latter half as 

 long. The second joint carries a small, supplementary joint-like 

 appendix {fil) , except in Hydnocera,, where it is well developed ; the 

 apical joint (///) is conical and small, except in Hydnocera,, where 

 it is twice as long as the second joint. 



The Mandible {md) is fitted both to grasp and chew a prey and to 

 gnaw galleries in wood ; it is well chitinized and well developed, half 

 or nearly half as long as frons. It is subtriangular ; the exterior, 

 lateral face is narrow and without elevated margin; the apex {apx) 

 is simple, more or less pointed, except in the deviating genus Priocera,, 

 where it is blunt; the pars scissoria has a longitudinal gi"oove {g) 

 on the ventral side; the retinaculum (r) is present on the middle 

 or close to the middle of the cutting edge, and a convex, serrate, or 

 tooth-like elevation is developed in many forms between retinaculum 

 and the tip of the mandible. Priocera is the only genus where 

 retinaculum is minute and granuliform and the whole cutting edge 

 nearly entire. No molar part, no prostheca, no mandibular brush is 

 present in any Clerid. There are usually two setae on the lateral 



