356 COLEOPTERA OF NORTH AMERICA. 



of the genera is quite concealed under the hood-like anterior 

 margin of the prothorax, and the side margin of the elytra is 

 expanded so as to coapt itself with the prothorax to form an 

 oval or nearly circular outline. The tribe is largely represented 

 in the tropics, but in our fauna comprises only a few species 

 belonging to the following genera : — 



Prothorax rounded in front, head quite concealed. 2. 



Prothoj-ax less rounded in front, head partially exposed, claws appendi- 



culate. 4. 



Prothorax emarginate in front, head visible. Porphyraspis. 



2. Prothorax with foliaceous margin. 3. 

 Prothorax with thickened sides. Physonota. 



3. Antennae not extending beyond the base of prothorax. Cassida. 

 Antennae extending beyond the base of prothorax. Coptocycla. 



4. Prothorax rounded behind. Mesomphalia. 

 Prothorax bisinuate at base. Chelymorpha. 



We have no certain evidence of the occurrence of Mesomphalia 

 in our fauna, but as it has been collected within a very short 

 distance south of the boundary, it is probably safe to infer that 

 some species will be found north of the Rio Grande. 



Some of the species of Cassida and Coptocycla are of a bril- 

 liant gold color, which varies with the emotions of the animal 

 and disappears entirely after death. 



Fam. LVII.— bruchidae. 



Mentum supported by a peduncle, transverse, more or less 

 emarginate in front, ligula coriaceous, bilobed or divided, 

 the palpi 3-jointed, moderate in lengtli. 



Maxilke exposed at base, bilobed, ciliate within, the palpi 

 •i-jointed, the terminal joint slightly oval. 



Head free, usually deflexed, muzzle slightly prolonged, 

 neck often constricted; epistoma distinctly separated by a 

 well-marked suture, labrum well developed ; eyes large, 

 more or less emarginate in front, and variably granulated. 



Mandibles moderate, depressed, arcuate, often with an 

 inner membranous border. 



Antennas ll-jointed, dentate or pectinate, inserted at the 

 side of the head in front of and near the eyes. 



Prothorax margined at the sides, the side pieces of the 

 sternum not distinct, the coxal cavities closed behind, the 



