214 PERCY SLADEN TRUST EXPEDITION 
clavam laxam formantibus. Palpi maxillares articulo secundo sat elongato ad apicem 
parum incrassato, articulo tertio quam secundo breviore, articulo ultimo quam tertio parum 
longiore. Mentum transversum, antice impressum ; palpi labiales breves, articulo secundo 
elongato, incrassato, dense ciliato, articulo tertio parvo, quam secundo multo breviore. 
Elytra sine stria aliqua. Ale omnino desunt. Prosternum breve, medio antice haud 
carinatum. Mesosterni pars elevata haud elongata, antice utrinque marginata, postice cum 
processu metasterni perfecte conjuncta, sutura transvers’ vix visibili. Metasternum in 
medio elevatum, antice inter coxas intermedias productum. Segmentum basale abdominis 
haud carinatum. Tarsi intermedi et postici hirsuti, articulo basali sat incrassato, quam 
secundo longiore. 
Body oval, not very convex, shining and glabrous above: under-surface subopaque, 
sterna and abdominal segments minutely reticulate, the latter with a very fine short 
pubescence. Hyes not emarginate in front. Antenne (Pl. 14, fig. 13) 9-jointed in 2, 
8- or 9-jointed in ¢ (see below, under B. mahensis), the last three joints forming a loose 
club ; basal jomt elongate, about equal in length to those intervening between it and the 
club taken together, second joint about as broad as basal joint, slightly pyriform, third 
shorter and much more slender, the following two (or one in B. mahensis 2) very short, the 
sixth (or fifth in B. mahensis 2) very short and transverse. Labrum (PL. 14, fig. 14) hidden 
under the front of the head, short and transverse, rather deeply sinuate in the middle of 
the front margin and fringed with hairs on either side. Mandibles (Pl. 14, fig. 15) with 
an elongate slender apical tooth, the inner margin below this membranous and fringed 
with hairs. Mazxille (PI. 14, fig. 16) with the lobes membranous, the upper one densely 
setose along its upper margin, the lower one with two setiferous processes at its upper 
angle and a fringe of setze on the margin below these; palpi (Pl. 14, figs. 16, 17) with 
second joint elongate and somewhat swollen apically, third joint shorter than second, 
fourth joint a little longer than third and blunt at the apex. Mentuwm (Pl. 14, fig. 18) 
transverse, impressed and concave in middle in front, with front margin slightly sinuate 
in middle; lobes of the ligula densely ciliate, projecting beyond the mentum; labial 
palpi short, second joint elongate, densely ciliate and slightly swollen, third joint very 
small, only about half as long as second, narrow, blunt at the apex. Hlytra without 
a sutural or any other stria. Wings entirely absent: the most careful examination of 
a number of specimens of both sexes, in both species, has failed to reveal any trace of these 
organs. Prosternwm very short, not carinate in the middle in front; a narrow lamina 
extends backwards between the front coxee, and the ventral part of it projects slightly 
behind (apparently slightly more in B. mahensis than in B. silhouette), but scarcely 
enough to be called a free process. Mesosternum (Pl. 14, figs. 20, 21) forming a rather 
short elevated ridge, strongly margined on either side in front, and very closely united to 
the forward-projecting portion of the metasternum, the transverse suture between the two 
being sometimes scarcely visible: the median portion of the metasternum is elevated and 
projects some way forward between the middle coxee to meet the mesosternum. [In 
B. silhouette the elevation of the mesosternum forms a sharp ridge, which continues as 
a carina without interruption along the metasternum to its posterior extremity (Pl. 14, 
fig. 21): in B. mahensis the elevated portions of mesosternum and metasternum are broader 
