ELATERIDAE. 171 



species are known to me : P. anguinus, from the Atlantic States, 

 of a dull black color, with short brown hair, with but single 

 branches proceeding from beyond the middle of the joints of the 

 antennas 4 — 11 each side ; and P. Murrayi Lee, from California, 

 of a more shining black color, much less hairy, with one inner 

 and two outer basal branches from the joints of the antennas. 



Group IV. — Corymbites. 



This group is so closely connected with the last by intermediate 

 forms, that its separation may be considered to be rather a matter 

 of convenience than of natural difference ; thus, the discussion of 

 the question whether Limonius vagits and estriatus Lee, which 

 form the new genus Eanus Lee, and L. dubitans, which forms 

 Nothodes, should enter this or the preceding group, is a matter 

 of but small consequence. 



The front is not margined behind the labrum, and is usually 

 slightly concave ; the mouth is anterior, though somewhat de- 

 flexed in Sericosomus (which differs from the group Agriotes in 

 this respect, as well as by the less convex front, and shorter first 

 joint of the antennas) ; the prosternum is either lobed or truncate 

 in front ; the sutures are double, not excavated in front, except in 

 Bladus and Nothodes, usually nearly straight ; the mesosternum 

 is not protuberant, sometimes acute in front ; the coxal plates are 

 gradually dilated inwards, sometimes toothed at the insertion of 

 the thighs. 



Our genera are : — 



Thorax without luminous vesicles ; 

 Tarsi filiform ; 



Prosteruum not lobed in front ; 

 Prosternal sutures straight ; third joint of antennae small. Biadtts. 

 Prosternal sutures concave outwards ; third joint of antennae equal to 

 fourth. OEstodes. 



Prosternum with a short lobe ; front suddenly deflexed at tip, but not 

 margined at the middle ; 

 Elytra not striate ; prosternal sutures not excavated. Eanus. 



Elytra striate ; prosternal sutures excavated in front. Nothodes. 

 Prosternum with a long lobe ; 

 Front convex ; coxal plates scarcely narrower externally. 



SERICOSOMrS. 



Front usually more or less flattened ; coxal plates narrow externally. 



Corymbites. 



Tarsi with the second and third joints lobed beneath. Asaphes. 



Thorax with luminous vesicles. Pyrofhorus. 



