.COLEOPTERA. 383 



Sometimes the mandibles are covered or project but little, as in 



MYCETOPHAGUS, Fabricins. 



In Mycetophagus proper, the club of the antennae commences at the sixth 

 or seventh joint ; the last is almost ovoid. 



There are several subgenera, such as Triphyllus, Dasycerus, Silvamts, &c. 



Sometimes the mandibles are entirely exposed, salient and robust. The 

 body is generally elongated, narrow, and depressed. These insects form the 

 genus 



TROGOSITA, Olivier. 



In Trogosita proper the mandibles are shorter than the head and crossed ; the 

 ligula, almost square, is not prolonged between the palpi, and the maxillae have 

 but a single lobe. 



FAMILY III. 



PLATYSOMA*. 



OCR third family of the Tetramera approaches the second, so far as relates 

 to the internal anatomy, the tarsi, and habits ; but the antennae are of equal 

 thickness throughout, or more slender towards the extremity. The mandibles 

 are always salient, the ligula is bifid or emarginated ; the palpi are short, the 

 body is depressed and elongated, and the thorax almost square. These insects 

 are found under the bark of trees, and may be reduced to a single genus, the 



GUCUJUS, Fabricius, 



Where the antennae, much shorter than the body in several, are composed of 

 obconical or turbiniform and almost granose joints, the first of which is shorter 

 than the head. 



There are two subgenera, Dendrophagus and Uleoiota. 



FAMILY IV. 

 LONGICORNESf. 



HERE, the under part of the three first joints of the tarsi is furnished with a 

 brush ; the second and third are cordiform ; the fourth is deeply bilobate, and 

 there is a little nodule resembling a joint at the base of the last. The ligula, 

 placed on a short and transversal mentum, is usually membranous, cordiform, 



* Flat-bodied. t Long-horned. 



