318 STAPHYLINIDZ. 
satisfactory solution of the difficulty. Probably about a score of species are known, the 
genus having a similar distribution to Bolitobius. The Central-American species are 
aberrant, but nevertheless the structure of their palpi is sufficiently congruous with 
what we find in the European species of the genus to allow me to avoid their separation 
at present. 
1. Megacronus oscillans. 
Niger; antennarum basi, palpis pedibusque rufo-obscuris, abdomine nigro-piceo apice rufescente; elytris 
crebrius seriatim punctatis. 
Long. 8 millim. 
Hab. Guatemaua, San Gerénimo (Champion). 
Three basal joints of antenne obscure yellow or red, penultimate joint scarcely so 
long as broad. Thorax much broader than long, very shining black. Llytra very 
elongate, but not twice as long as the thorax, regularly covered with incomplete 
punctures. Hind body rather sparingly punctate, very acuminate. 
The colour of the legs, palpi, and base of the antennz readily separates this insect 
from MV. nigerrimus; the form of the maxillary palpi is also a little different, they being 
in WV. oscillans more truly of the form characteristic of the genus, though unusually long 
and slender. 
Only a single individual has been found. 
2. Megacronus nigerrimus. (Tab. VII. fig. 18.) 
Totus nigerrimus; elytris crebre fortiter seriatim punctatis, abdomine crebrius punctato. 
Long. 10 millim. 
Hab. Panama, Volcan de Chiriqui 3000 to 4000 feet (Champion). 
Head very short; penultimate joints of antenne evidently transverse. ‘Thorax black, 
very shining, with a transverse series of six, very distant, fine punctures near the front 
margin, and a similar series in front of the basal margin. Elytra longer than the 
thorax, each with seven or eight series of very distinct punctures ; the sutural series 
rather denser and more regular than the others, the two or three external series less 
regular. Hind body with the basal segment broadly impunctate in the middle; the 
other segments rather closely punctate, especially on the basal portion of each. 
Only one specimen has been met with. 
3. Megacronus acuminatus. 
Gracilis, piceus; antennarum basi palpisque testaceis; elytris ad basin rufescentibus, fortiter, regulariter 
seriatim punctatis; abdomine crebre punctato, apice rufo; antennis fere gracilibus articulis nullis 
transversis. 
Long. 63 millim. 
Hab. Panama, Volcan de Chiriqui 2000 to 3000 feet (Champion). 
