266 HETEROMERA. 
*** Prosternum narrower and acuminately produced, the apex slightly raised. 
7. Oxidates puncticeps. 
Bronze-black, rather dull. Head closely and comparatively coarsely punctured ; antenne long and slender ; 
prothorax broader than long, feebly transversely convex, the sides rounded, constricted just before the 
base, rather narrower in front than at the base, the hind angles subacute, the anterior angles broadly 
rounded, the base strongly margined, the surface finely, closely, and very evidently punctured ; scutellum 
small; elytra obliquely and abruptly narrowing behind, the apex not much produced, with rows of very 
coarse rounded impressions, the impressions slightly tinged with metallic golden within and not finer 
along the suture; beneath shining, very sparingly and finely punctured; prosternum comparatively 
narrow, subhorizontal, subrugulose, grooved on each side within, strongly and acuminately produced, the 
apex slightly raised ; mesosternum almost simple; epipleure reaching to the last ventral suture, almost 
obsolete beyond; legs black. 
Length 83 millim. (¢ 2.) 
Hab. Muxico, Jalapa, Misantla (Hoge). 
Two examples. This species differs from its allies in having the head comparatively 
coarsely punctured, the elytra less abruptly narrowed behind and with the apex less 
distinctly produced, the prosternum narrower and acuminately produced. 
ISAMINAS. 
Isaminas, F. Bates in litt. 
Mentum and palpi as in Oxidates; inner lobe of the maxille with a strong curved claw at the apex (as in 
Oxidates); mandibles truncate at the apex; antenne comparatively short, longer in the male, the third 
joint long, much longer than the fourth (in Oxidates but little longer), joints 9 and 10 about as broad as 
long in the male, more or less transverse in the female; epistoma large (less transverse than in Oxidates), 
sharply defined (at the sides by a deeper groove); prothorax very strongly transverse, nearly twice as 
broad as long, comparatively rather flat, very distinctly margined ; scutellum small; elytra short, trans- 
versely gibbous, raised considerably above the level of the prothorax, the apex produced, with rows of 
coarse rounded impressions (as in Oxidates and Spherotus); prosternum very broad, horizontal, longitu- 
dinally grooved on each side within, the central part convex, very broadly produced, parallel or acuminate, 
the apex received by the more or less deeply excavate mesosternum ; metasternum very short, deeply 
transversely impressed ; intercoxal process broad, impressed on each side within; epipleure distinctly 
and rather broadly extending to the apex in I. gibbipennis, more or less confounded with the elytra and 
defined towards the base only in JI. brevicollis; first joint of the posterior tarsi short; tibie almost 
straight in both sexes; body apterous; the rest as in Owidates and Spherotus. 
This genus includes two closely allied Central-American species. JIsaminas though 
unquestionably very closely allied to Oxidates will be readily known from that genus 
by the exceedingly broad and short thorax, the much shorter and differently formed 
antenne (the third joint distinctly longer compared with the fourth), the still broader 
prosternum, the straighter tibiee, &c. These insects are found by beating the withered 
still-attached leaves of the decaying branches of trees in dark places in the dense 
humid forest. 
