452 SEEKICOENIA. 



punctate elytra. In one of the males from Chontales, deep black in colour, the basal 

 sulci of* the thorax are limited externally by a prominent longitudinal plica, and the 

 space between this and the almost obsolete carina extending obliquely forwards from 

 the tip of the hind angles is deeply triangularly excavate. 



MELANOTUS. 



Melanotus, Eschscholtz, in Thon's Archiv, ii. 1, p. 32 (1829) ; Candeze, Monogr. Elat. iii. p. 298 



(part.). 

 Perimecus, Stephens, Illustr. Brit. Ent., Mand. iii. p. 263 (1830). 

 Cratonychus, Boisduval et Lacordaire, Faune Ent. env. Paris, i. p. 631 (1835) ; Leconte, Trans. 



Am. Phil. Soc. new ser. x. p. 473. 

 Priopus, Castelnau, Hist. Nat. Ins. Col. i. p. 251 (1840). 



Of the 165 described species of this widely-distributed genus, forty-six are American, 

 and of these latter all but three are nearctic. As already noted under Spheniscosomus, 

 a certain number of them have been separated. In America Melanotus does not 

 appear to extend south of the Mexican State of Vera Cruz. One species, M. castanipes 

 (Payk.), is holarctic, extending into Northern Mexico. 



a. Antennae with the third joint short, not much longer than the second; the basal 



sulci of the pro thorax short. 

 a'. Prothorax longitudinally carinate down the middle behind ; the hind angles 



with a very long carina, extending forwards to the middle of the prothorax . carinifer. 

 b'. Prothorax not carinate in the middle behind; the hind angles with a short carina. 

 a". Elytra more than three times the length of the prothorax, the interstices 

 simply punctured. 

 a'". Prothoracic punctuation very coarse ; elytra narrowing from before the 



middle prolixus. 



b'". Prothoracic punctuation moderately coarse ; elytra subparallel to beyond 



the middle . castanipes. 



b". Elytra not more than three times the length of the prothorax, the inter- 

 stices transversely rugulose and punctured; the prothoracic punctuation 

 rather fine rugulipennis . 



b. Antennae with the third joint nearly twice as long as the second; the hind angles 



of the prothorax with a short carina, the basal sulci short mexicanus. 



1. Melanotus carinifer. (Tab. XX. fig. 3, prothorax, <s .) 



6 ■ Moderately elongate, flattened above, shining, sparsely pubescent, above pitcby-brown, beneath rufo- 

 castaneous, the legs and antennae ferruginous. Head coarsely, closely umbilicate-punctate ; antennae 

 two-fifths the length of the body, the third joint a little longer than the second. Prothorax 

 slightly broader than long, gradually narrowing from the base, the sides feebly rounded, slightly sinuate 

 behind ; the hind angles long and divergent, with a sharp supra-marginal carina extending forwards to the 

 middle of the prothorax, and a short, sinuous carina or plica within ; the basal sulci very short and 

 inconspicuous ; the surface coarsely and rather closely punctured, the punctuation becoming closer, coarser, 

 and umbilicate towards the anterior angles, the disc sharply longitudinally carinate in the middle behind 



