408 REVISION OF THE ELATERID/E 



exposing slightly the articulation; in the Eucnemides (except Anelastes) the margin is re- 

 gular, and the articulation entirely concealed; the abdomen has only five ventral seg- 

 ments, except in Cehrio and an allied genus, where the fifth joint is truncate and the sixth 

 becomes prominent. The femora articulate at the apex of the trochanters, which are thus 

 fulcrant; the tarsi are never much dilated, occasionally furnished with membraneous lobes 

 beneath, and usually pubescent; the fifth joint is slender with two equal claws, varying in 

 form, and usually with a small intermediate appendage terminated by two seta?. The 

 tibia 1 are usually slender, never fossorial, rarely compressed; in one genus, allied to Ce- 

 brio, a tendency to the fossorial form is shown. 



The mentum is small, trapezoidal, and inflexed; the base of the maxilla? exposed; the 

 latter have two distinct lobes, the outer one is never palpiform; the last joint of the max- 

 illary palpi is usually dilated, and larger than the preceding; in Tharops and Melasis, 

 however, the terminal joint is oval and pointed, and not much larger than the one before 

 it; in Adrastus alone, of the true Elaterides, it is long and acuminate; and, finally, in the 

 Cebrionides it is cylindrical and truncate; the labial palpi are very small except in the 

 Cebrionides. 



From this detail of characters, we would at first be inclined to select for the definition 

 of our three primary groups, (admitting them to be three in number,) the insertion of the 

 antenna?, and the structure of the abdomen, as being those of probably the greatest value. 

 Genera are soon found, however, in which all the other characters of Cebrio are found, 

 and which have the abdomen constructed as in other Elaterides; the form of the mandi- 

 bles is obviously a character of too little value for a primary division; we are thus forced 

 to divide the entire family into two great groups: Eucnemides, having the antenna 1 in- 

 serted in a sinus, and somewhat approximated, and the clypcus dilated anteriorly; Elaterides, 

 having the antenna? inserted at the margin of the eyes, under the front, which is not dila- 

 ted anteriorly, and not narrowed at the middle. 



The Eucnemides contain three distinct types: Melasis, with the small acute terminal 

 joint to the maxillary palpi, the imperfectly protected mouth, and the hardly approximated 

 antennae; Eucnemis, with moderately approximate antennae, and convex deflexed front; 

 Cerophytum, with closely approximate antenna, and somewhat gibbous front. 



The Elaterides divide naturally into two groups: the true Elaterides, with small re- 

 tracted mandibles, and small labial palpi; and the Cebrionides, with long porrectcd man- 

 dibles, and cylindrical palpi, all of which are moderately elongated. 



These tribes, with the exception of the true Elaterides, are so small, that their resolu- 

 tion into genera is attended with no difficulty: it is very different, however, with that 

 large and difficult group, nor have any previous attempts to arrange its contents been 

 attended with any success. 



On examining the other groups, with a view to ascertain whether any light could be 

 gained from them, I found, in the genuine Eucnemides, a remarkable correspondence in 

 the elongated basal joint of the antennas and the absence of any tooth at the internal 

 part of the coxal plates: the genus Anelastes makes the only exception to this latter cha- 

 racter; and the various places given to that curious genus by different authors sufficiently 



