NORTH AMERICAN COLEOPTERA. 45 



a short carina, disc nioderately convex, closely punctate, basal incisures short, 

 feeble, median line impressed posteriorly. Elytra wider than the thorax, arcuately 

 narrowing to apex, deeply striate, strise moderately coarsely and closely punctate 

 intervals convex, sparsely punctate. Body beneath densely finely punctate, less 

 shining than above. Length .22-. 30 inch; 5.5-7.5 mm. 



This species belongs to the first section of the genus as characterized 

 by Candeze, having the sides of thorax without acute margin. It seems 

 most closely related to spadiceus, but the thorax is distinctly longer than 

 wide. 



Occurs in Dimmit County, Texas; several specimens. 



The genus Aptopus resembles Cardiophorus in all respects except that 

 the tarsal claws are pectinate as in Melanotus. The species already 

 known are few in number and occur in Mexico and Brazil. 



liUDIUS Latr. 



The genus as here recognized contains the same elements as in the 

 monograph of Candeze less limbah's, which Dr. LeConte has properly 

 removed to Megapenthes, and tartareus, at one time placed in Ludius, 

 which has also been placed in the same genus. 



The antennae are very uniform in construction, the second and third 

 joints are always small, the third a little longer than the second, the two 

 together shorter than the fourth. The fourth joint usually longer than 

 any of the following joints. The terminal joint is always suddenly 

 narrower near the apex presenting the appearance of a false joint. 



The females have shorter antennae than the male, the joints from 4—11 

 being shorter, although as wide as in the male, have the appearance of 

 being more strongly serrate. 



The form of the free angle of the hind coxal plate varies in the 

 species. In some the angle is quite acute in others obtuse or rounded, 

 the transition is, however, so gradual that no use can be made of it sys- 

 tematically. 



Two Californian species are remarkable in having the entire lateral 

 margin of the thorax visible from above, in all the other species it is 

 deflexed. 



The structure of the mesosternal fossa in attenuatus is unique in our 

 fauna, and it is remarkable that the only other species with similar 

 structure occur in intertropical Asia. 



The following table will enable our species to be separated with ease. 

 In their distribution, three belong to the Pacific region, two to the 



