PYCNOCEPHALUS. 375 
PYCNOCEPHALUS, gen. nov. 
Corpus contractile. Caput latissimum. Tarsi quadri-articulati, compresso-dilatati. Antenne parvee, articulo 
basali magno, auriculato, secundo subnodoso; clava tri-articulata, parum lata. Pedes lati, posteriores 
femoribus tibiisque laminato-dilatatis. 
This genus seems to be well distinguished from Cybocephalus by the dilated, lamini- 
form femora and tibie of the posterior two pairs of legs. It differs also in other 
characters: the head is excessively broad and short, the eyes widely separated, the first 
joint of the antennee of peculiar shape. The metasternum in the middle is acuminate 
and produced so that the perpendicular part of the mesosternum forms a cavity, the 
anterior part of the mesosternum being broadly longitudinally impressed. The middle 
femur is greatly dilated (fig. 6a, middle leg), and in contraction the tibia and tarsus 
are withdrawn entirely behind it, and appear to be absent; the mesosternum and 
the anterior part of the metasternum are impressed for the reception of the middle 
legs, and the metasternum and the first ventral segment for the accommodation of the 
posterior legs. The tarsi, though dilated, are very strongly compressed. 
1. Pycnocephalus metallicus, sp.n. (Tab. XII. figg. 6; 6a, middle leg.) 
Globosus, niger, supra metallicus, nitidus, tibiis, tarsis antennisque testaceis, harum articulo basali nigro ; 
corpore supra fere levigato, elytris absque stria suturali. 
Long. corpore subcontracto 2 millim. 
Hab. Guatemata, San Gerénimo, Tamahu (Champion); Panama, Bugaba, Volcan 
de Chiriqui (Champion). 
Head excessively broad. Antenne small, the basal joint large, auriculate, black, 
the other joints yellow, the club small. Thorax very convex, very short at the sides 
but elongate along the middle, smooth, and very shining, the punctuation being 
excessively minute. Scutellum extremely broad and short. LHlytra short, extremely 
convex, similar in sculpture to the thorax. 
Subfam. JPSIT NZ. 
This division is very sharply defined, and differs strongly from all the other Nitidu- 
lide in the structure of the head; the epicranium is prolonged much in front of the 
insertion of the antenne, while the clypeus is reduced to a very small piece quite at 
the front of the head; the labrum, as described by Erichson and others, being covered 
by the clypeus. 
All the species of this group possess a stridulating-organ on the summit of the, 
vertex. I have observed nothing of this kind in any other Nitidulide. 
