444 BULLETIN UNITED STATES GEOLOGICAL SURVEY. 



Mackenzie Eiver Region, Robert Kennicott ;. Canada ; near Saskatch- 

 ewan River, and in the Province of Ontario. 



Specimens occur which are destitute of white spots upon the corium 

 and clavus. I found numerous specimens upon the mud of the black 

 marshes of Brighton and. Cambridgeport, Mass., in the month of July. 



The remarks under /S. lugubris Say, in my paper printed in Dr. Hay- 

 den's Bulletin, vol. ii, No. v, p. 67, belong to this species. 



15. S. inter stitialis. 



Acanthia interstitialis Say, Jonm. Acad. Phila., iv. 324, No. 1. 



Ovate, dull black, closely bronze pubescent, with a few remote, erect, 

 black hairs on the head, pronotum,and base of the hemelytra. Head 

 from above broad and short, vertical, with a very short neck behind ; 

 the eyes large, brown, moderately projecting above the line of the ver- 

 tex; base of head moderately convex, minutely shagreened, separated 

 from the ocelli by a transverse impressed line ; front almost flat, densely, 

 minutely scabrous, the longitudinal groove obsolete; reflexed edge of 

 the clypeus yellow or piceous; tylus a little prominent, slightly nar- 

 rower iuferiorly, yellowish, a little shorter than the labrum, bald ; la- 

 brum broad, yellow, a little ridged on the middle line, with the sides 

 sloping, the tip bluntly triangular and set with stiff hairs. Upper mar- 

 gin of the buccul?e yellow ; rostrum reachii)g behind the end of the pos-> 

 terior coxfe, dark piceous, paler at tip. Antennae slender; basal joint 

 short and stout, dull yellow, with a black line beneath and sometimes 

 obscure on the middle above ; second join', a little shorter than the third 

 and fourth conjoined, yellowish or pale pneous, darker on the middle, 

 slightly thickened at tip; third and fourth subequal, dull black, each 

 longer than the basal one, and stouter than the second, subfusiform. 

 Pronotum lunate, densely coated with prostrate golden pubescence and 

 with longer black hairs on the margins and before ; lateral margins mod- 

 erately and abruptly reflexed, the submargin broadly depressed, of uni- 

 form width throughout, minutely scabrous; surface generally minutely 

 scabrous ; the callosities forming a transverse ridge, sharply bounded 

 by an impressed punctate line, which curves around the sides and stops at 

 an indented point some distance behind the anterior margin ; posterior 

 margin deeply concave, the lobed humeral angles obliquely truncated 

 and with a long tubercle near the outer corner. Scutellum feebly con- 

 vex, closely minutely scabrous. Innately impressed, the apical division 

 a little flattened, obsoletely rugulose, with the edge yellowish. Pectoral 

 pieces polished, black, clothed with prostrate whitish pubescence, the 

 prosternum slenderly margined with white. Legs dull yellow, gener- 

 ally with a black line on the under side of the femora and tibite ; the 

 femora often with piceous dots on the front and back faces ; tibiae 

 tipped with piceous, with piceous spines, and sometimes with piceous 

 spots or faint bands at the base of the spines ; tarsal joints tipped with 

 piceous and the basal joint entirely piceous, the nails pale piceous. 



