244 
and Carina near the base dull testaceous. Body beneath dull 
black ; base of thighs reddish testaceous. 
Banks of the Tapajos and Ega, Upper Amazons. Mr. Fry 
informs me that the peculiar bilobed prominence of the head is 
found in the males of some Bio Janeiro species. Hemilophus 
frontalis of Guerin-Meneville (Ins. rec. par Osculati, n. 265) 
belongs to this genus. 
Genus Isomerida, nov. gen. 
This new genus is distinguished from Hemilophus by the an- 
tennal joints decreasing in length in regular proportion from the 
third joint to the apex, and by the fringe of hairs on their under 
surface existing in uniform density on all the joints. The only 
difference between Isomerida and Amphionycha lies in the short- 
ness of the antennse, which are not longer than the body, even 
in the males, and decrease greatly in thickness from the third 
joint to the apex. 
I have adopted the name under which the genus stands in 
the collection of Mr. Alexander Fry. 
1. Isomerida albicollis, Castelnau. 
Hemilophus albicollis, Laporte de Castelnau, Animaux articules, ii. p. 488. 
/. elongata, linearis, postice paulo angustata, tenuiter setosa ; capite 
thoraceque rufo-testaceis, cano interdum dense tomentosis ; elytris 
punctatis, interstitiis duobus elevatis, apice truncatis, rufo-testa- 
ceis plus minusve fuliginosis, vel totis nigris; abdomine nigro, 
segmentis tertio et quarto dense cano tomentosis ; antennis nigris, 
articulis basi testaceis. Long. 4^-5^ lin. c? $ . 
This common species is very variable in its coloration, and there 
is only a small proportion of examples which exhibit the white 
hue of the thorax, and these only in the dried state ; in life, the 
thorax is always red. The truncature of the elytra is straight 
and offers a short tooth at the exterior angles. 
It is found on the leaves of trees, and is a common and gene- 
rally distributed insect throughout the Amazonian forests. 
2. Isomerida ruficornisj n. sp. 
7. robustior, elongata, linearis, postice baud angustata, tenuiter setosa, 
nigra ; capite, thorace, antennis (apice exceptis) et pedibus (femo- 
ribus supra exceptis) rufis ; elytris apice truncatis, angulis externis 
dentatis ; abdomine segmentis tertio et quarto dense cano tomen- 
tosis. Long. 6 lin. d' . 
Head entirely red, depressed between the eyes. Antennse 
stout, as long as the body, finely fringed beneath ; third joint 
one-third longer than the fourth, the following becoming very 
