AMERICAN COLEOPTERA. 81 



Elytra with broad bluish vitta sometimes narrowed 

 at middle. 

 Thorax rufous, immaculate. 



Rufous margin of elytra narrow, blue vitta 



scarcely narrowed at middle limbellus, Geinm. 



Rufous margin broad, vitta, narrow at middle. 



Sides of thorax strongly rounded laticollis, Horn. 



Sides of thorax feebly rounded confluens, Lee. 



Thorax with discal black spot. 



Elytra alutaceous, unequally punctured punctulatus, Lee. 



Elytra scabrous, densely punctured • { ^f^SlSTLec. 



C tricolor and punctatns resemble each otlier very closely. The 

 characters given in the table being the'only ones in which they differ. 

 In color the head is nearly black ; thorax rufous immaculate ; elytra 

 aeneous or bluish black. Two specimens before me of tricolor have 

 a short narrow space at the middle of the lateral margin of the elytra, 

 rufous. The former spaces is widely diffused, occurring from Canada 

 and the Middle States to Kansas, the latter is from Kansas. Addi- 

 tional collections may show them to be identical. 



C. cximius and niyriceps resemble each other, differing scarcely as 

 much as the two preceding species. Their colors are similar to the 

 above species, the thorax having in addition a discal black spot vary- 

 ing from a longitudinal broad band to a size covering all but a narrow 

 margin. Occurs in the Middle and upper Southern States. 



C. marginicolUs is larger than eximius, the anterior margin of the 

 front not rufous, thorax with only a narrow pale margin, and the ely- 

 tra much more densely punctured and opaque. Occurs in California. 



C. cribrosus is a somewhat variable species. The typical and most 

 abundant form has the thorax almost entirely black with a very nar- 

 row rufous margin reduced at times to a narrow space at each angle. 

 The elytra are aeneous black or nearly blue and unicolorous rather 

 coarsely and densely punctured. Specimens occur with the anterior 

 legs and middle femora fuscous and others with the legs entirely 

 black. In several specimens from Owen's Valley, a narrow, short 

 space at the lateral margin and a similar space at the middle third of 

 the elytra, are rufous. Specimens with well developed wings have the 

 humeri more distinct, several specimens without wings have thejely- 

 tra nearly oval. These cannot be properly separated as the transition 

 is gradual from those in which well developed wings occur through 

 others with imperfect wings to those with none at all. This species 

 occurs along the sea coast of California. The better developed arc 



