ACHEESTUS.— MONOCKEPIDIUS. 341 



Hab. Nicakagua, Chontales (Belt). 



One male specimen. Allied to A. phyllocerus, Cand., from Venezuela, but narrower, 

 the head and thorax much more sparsely punctured and more shining, the elytral 

 interstices narrower and more convex, the antennae flabellate in the male. The 

 markings on the anterior half of the elytra form an interrupted ante-median fascia. 

 A more nearly allied undescribed form from the Amazons is contained in the Janson 

 collection. 



Group MONOCREPIDIINI. 



MONOCREPIDIUS. 



Monocrepidius, Eschscholtz, in Them's Archiv, ii. 1, p. 31 (1829); Candeze, Monogr. Elat. ii. 



p. 187. 

 Conoderus, Eschscholtz, loc. cit 



A genus containing upwards of 200 described species, more than half of which are 

 American. In the typical forms, M. lividus, M. apiatus, &c., the fourth tarsal joint is 

 broadly lamellate beneath ; but in some of the species the lamella is shorter and 

 narrower, and in the small forms placed at the end of the genus (M. pictus, M. bellus, 

 &c.) it is reduced to a narrow filament not wider than the apical joint. These small 

 species have entirely the facies of Drasterius, of the group Elaterini, from which they 

 differ only in the lamellate fourth tarsal joint. The outer prosternal suture is well 

 defined in M. jpictus and M. bellus, indistinct in our other species. The genitalia of 

 the males afford good differential characters in some of the closely allied forms. In 

 two species, M. apiatus and M. pilatei, the terminal dorsal segment is deeply sulcate 

 down the middle. 



Thirty-two species are here enumerated from within our limits, twelve of which are 

 described as new. 



A. Fourth tarsal joint strongly lamellate beneath, the lamella visible from 

 above. 



a. Elytra abruptly emarginate at the apex, the sutural and outer angles 



dentiform ; antennae with joints 2 and 3 equal in length Species 1, 2. 



b. Elytra more feebly emarginate at the apex; antennae with joint 3 nearly 



twice as long as 2. 

 a'. Apex of the fifth ventral segment rounded ; outer apical angle of the 



elytra obtuse Species 3. 



b'. Apex of the fifth ventral segment more or less mucronate at the middle ; 

 outer apical angle of the elytra distinct. 

 a". Punctuation of the prothorax moderately close, the punctures unequal 



in size Species 4. 



b". Punctuation of the prothorax dense, the punctures very fine and equal 



in size Species 5. 



