AMERICAN COLEOPTERA. 233 



very little narrowed posteriorly, sides very slightly sinuate at middle, base 

 subtruncate at middle, sides and base rather widely margined, disc moderately 

 convex, anterior impression deep, median line fine, surface minutely punctate 

 margin more coarsely. Scutellum densely punctulate at base. Elytra nearly 

 as wide at the base as the thorax, slightly broader jjosteriorly with very feebly 

 arcuate sides, apex sinuately truncate, surface somewhat variably but usually 

 coarsely punctured and with two faint costae and a few coarser punctures form- 

 ing indistinct series. Abdomen above and beneath very sparsely punctate. 

 Metasternum with brownish pubescence. The outer apical angle of the an- 

 terior tibipe is moderately prolonged, the spurs are a little unequal, the outer 

 larger. The middle and posterior tibiae are gradually stouter to tip and straight. 

 Length .80—1.00 inch; 20—25 mm. 



This species exhibits a range of color variation of the elytra greater 

 than any other species known to me. 



X. niijrita Mann. — This form is entirely black and less shining than 

 the others. The antennal club is red except the first joint. 



Its distribution is from the middle of California southward to the 

 Peninsula and Guadeloupe Island, thence eastward through Arizona 

 to Texas. 



N. piistulafus Herschel. — Here the elytra are black excepting a red 

 spot of variable size at the side of the elytra at the usual position of 

 the first band, and two spots posteriorly near the apical marcjin of 

 variable size. The epipleural fold is black. This form is usually a 

 little more coarsely punctured than the preceding. JV. tardus Mann., 

 is a synonym of this variety. 



This form is the one occurring more especially in the Atlantic region 

 from the New England States to Texas, where we find entirely black 

 forms resembling nigrita in color and pustulutus in sculpture. It 

 occurs also in Alaska. 



N. Mehheimeri Kby. — Under this head are included those forms in 

 which the epipleural fold is red, either entirely or in very great part. 

 The variety most nearly approaching pustulatus has in addition the 

 lateral spot of the latter species, while the small subapical spots are 

 united in a narrow fascia. With this as a starting point we have the 

 lateral spot extending forming a band of varying width and finally 

 reaching the suture. The posterior band also becomes gradually wider 

 so that we have forms in which the elytra are almost entirely red 

 as in guttula. 



This variety occurs from Colorado northward to the Hudson's Bay 

 region and Alaska, thence southward through Oregon and the north 

 of California. 



In this species the scries of variations in the color of the elytra 



TRANS. AMEU. ENT. SOC. Till. (30) AUGUST, ISSO. 



