160 GEO. H. HORN, M. D. 



groups, tribes, or sub-families, have become so numerous and are based 

 on such shadowy characters as to envelope the subject in an almost 

 impenetrable cloud. 



Tribe XXXV.-Helluonini. 



Antennse moderate in length, rather stout, usually compressed arising under 

 a distinct frontal plate, all the joints more or less pubescent, two or four at the 

 base less densely, first joint stout, equal in length to the next two. Head broadly 

 oval, not narrowed in front of the eyes, with a distinct neck more or less abruptly 

 formed, clypeus moderately prolonged, a setigerous puncture at each side, front 

 with two supra-orbital setigerous punctures. Eyes round, moderately prominent, 

 close to the mouth beneath. Labrum usually large and prominent, more or less 

 concealing the mandibles, sexsetose in front. Mandibles stout, arcuate, rarely 

 prominent, acute at tip. Mentum broad, deeply emarginate usually toothed, 

 ligula prominent, bisetose at tip, the paraglossfe adherent to the sides rarely 

 [Polystichus) longer than it and usually semicorneous, the palpi of moderate 

 length, the terminal joint elongate-oval or fusiform and obtuse at tip, the penulti- 

 mate bisetose in front. Maxillae hooked at tip, ciliate or spinous within the outer 

 lobe rather stout, biartieulate, the palpi stout, the terminal joint oblong-oval 

 truncate at tip, more or less flattened. Thorax more or less cordate, sides and 

 hind angles with a distinct setigerous puncture. Elytra oblong, truncate at apex, 

 base not margined, sides narrowly infiexed, margin entire, disc striate or broadly 

 sulcate, without dorsal punctures. Prosternum not prolonged. Mesosternal epi- 

 mera narrow. Metasternal epimera distinct, the posterior coxse contiguous. Legs 

 moderate in length, the anterior femora more or less clavate. Tibife sometimes 

 (Helluomorpha) compressed and finely bicarinate on the outer edge, the anterior 

 rather stout and broad, deeply emarginate within, spurs moderate in length. 

 Tarsi moderate in length usually ciliate above, the fourth joint either entire, 

 emarginate or even bilobed. Claws simple. 



The anterior tarsi of the male are rarely broader than the female. 



This tribe is the equivalent of the Helluonides of Lacordaire, to which 

 I add PoJi/stichus. 



The form of the ligula has been almost the entire reliance in the 

 separation of this tribe from the other Truncatipennes, but the method 

 usually adopted in describing the ligula as having no paraglossge is 

 entirely erroneous. Although the labium (which term includes the 

 entire organ, ligula and paraglossse), is almost entirely corneous in the 

 majority of genera, the parts which compose it are as evident as in A<jra 

 in which the whole organ is almost entirely membranous. 



Polystichus is added from the Dryptini, as it lacks the palpar structure 

 which is characteristic of that tribe ; it has moreover the front parallel 

 before the eyes, forming a plate over the antennas, the anterior legs 

 rather stout and the antennas distinctly compressed. These latter are 

 decided characters approaching it to the present tribe. It is however one 

 of those forms which should be placed in the position of an intermediate. 

 Its ligula and paraglossfe are unlike the present tribe the paraglossae 



