34 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 121 



Types. — Lectotype of ignobilis: Male, no data (MCZ). Un- 

 labelled specimen in LeConte Collection, assumed to be type, agrees 

 with our interpretation of the species; to forestall possible confusion, 

 specimen selected as lectotype by authors in 1962. 



Lectotype of secretus: Male, labelled with orange circle "Southern 

 States" (MCZ 2510). First specimen of type series selected as 

 lectotype by authors in 1962. 



Distribution. — New York south to Florida and west to South 

 Dakota and Texas. 



Alabama: Colbert, Mobile; May, June. Arkansas: Washington; June, July. 

 Florida: Highlands, Alachua, Putnam, Volusia; April, May. Georgia: 

 Charlton, Fulton; July. Illinois: Marshall, Putnam; June, July. Indiana: 

 Clark; June. Louisiana: Madison; June, July. Mississippi: Greene, Jack- 

 son, Perry; May, July. Montana: Phelps, St. Louis; June. Nebraska: 

 Lancaster; July. New Jersey: Ocean; June, July. New York: Niagara, 

 Tompkins; July. North Carolina: Wake; June. Pennsylvania: Dau- 

 phin; June. South Carolina: Charleston, Oconee; March, July. South 

 Dakota: Brookings; July. Tennessee: Morgan; June, August. Texas: 

 McCuUoch; July. 



M. ignobilis is a distinctive species easily recognized by the short 

 third antennal segment, quadrate yellowish flagellar segments, lack 

 of mandibular pit, and dense pronotal punctures. The female in- 

 ternal genitalia are quite different from any other North American 

 Melanotus, and the male genitalia are also markedly different from 

 other species. 



We can find no significant differences between secretus and ignobilis. 

 The former name was apphed to smaller specimens of ignobilis which 

 often have the prothorax as long as wide and are usually lighter in 

 color. The male and female genitalia of these smaller, hghter colored 

 specimens do not differ from ignobilis, and we consider them as a part 

 of the variation range of that species; hence, secretus is synonymized 

 with ignobilis. 



The americanus Group 

 (Mandible with pit) 



16. Melanotus depressus (Melsheimer) 



Figures 5i, 10b; Plate Ij 



Ctenonychus depressus Melsheimer, 1846, p. 151. 



Cratonychus depressus. — LeConte, 1853, p. 475. 



Melanotus depressus.— Candhze, 1860, p. 345.— Blatchley, 1910, p. 755.— Thomas, 



1941, p. 258.— Dietrich, 1945, p. 55.— Fattig, 1951, p. 20. 

 Ctenonychus parumpunctatus Melsheimer, 1846, p. 151. 

 Cratonychus parumpunctatus. — LeConte, 1853, p. 478. 

 Melanotus parumpunctatus. — Candfeze, 1860, p. 355.— Blatchley, 1910, p. 754. — 



Thomas, 1941, p. 260.— Dietrich, 1945, p. 57.— Fattig, 1951, p. 21. 



