148 COLEOPTERA OF NORTH AMERICA. 



Mandibles feeble, in great part membranous ; last spiracle midway between 

 the anterior and posterior margin of the segment ; 



Prothorax lobed at the base, covering the scutellum. Gymnetes. 



Scutellum not covered by the thorax. Cetonije. 



Mandibles with the outer part thickened ; last spiracle near the posterior 



margin of the segment, the suture nearly effaced. Ckemastochili. 



Group I.— Gymnetes. 



But two genera of this group occur in our fauna. Allorhina 

 having the clypeus armed with a short horn ; Gymnetis with the 

 clypeus flat. 



Allorhina nilida extends over the Atlantic slope, and is a 

 well-known green, velvety insect, nearly an inch long, somewhat 

 pointed in front, with the sides of the thorax and elytra usually 

 brownish yellow. Other species will probably be found in our 

 southwestern territories. 



Gymnetis Sallei is found in Louisiana, Texas, and Mexico. 

 It is a beautiful velvety, olive-colored insect, of the same form 

 as Allorhina, three-fourths of an inch long, variegated with pale 

 yellow marks, which unite on the margin of the thorax and elytra. 



No species of this group has yet been found on the Pacific 

 slope. 



Group II. — Cetoniee. 



Our species, although arranged by Burmeister in three genera 

 — Euphoria, Erirhipis, and Stephanucha — have been united by 

 Lacordaire with other foreign forms, and for the combined genus 

 he retains the name Euryomia, distinguished from the other genera 

 by the maxillae not toothed, and the clypeus usually parabolic, 

 sometimes parallel, and rarely emarginate in front. They are all 

 of moderate size, nearly parallel behind, and pointed in front. 



None have yet been found on the Pacific slope. 



Group III.— Cremasto chili. 



Besides the greater development of the mandibles, and the 

 position of the last spiracle near the posterior extremity of the 

 obliterated suture between the fifth ventral and propygidium, the 

 mentum in our species affects a very unusual form ; it is, in fact, 

 a large cup-shaped body, sometimes acute behind, sometimes in- 

 cised, but passing by gradation from one to the other form. The 

 mesosternum is not protuberant. 



