234 PROC. ENT. SOC. WASH., VOL. 22, NO. 9, DEC., 1920 



narrowed behind, the median depression almost abruptly terminated at 

 about the middle instead of being continued backwards as in O. eremicola; 

 the surface of the pronotum has deep, rather variolose punctuation extend- 

 ing entirely across the disk behind the depression in place of the minute 

 points seen in O. eremicola; and the scutellum, while of similar form, is more 

 coarsely punctate, lacking the smooth median area. In 0. montana, the 

 elytra are rougher, the punctuation coarser, less regularly arranged in stria 

 near the suture; the pygidium is more elongate-triangular and less densely 

 hairy. Body beneath, similar in the two species. Total length, 21.75 mm; 

 elytron, along line of greatest length, 13.25 mm.: humeral width, across 

 elytra, 9.25 mm. ; greatest width, 10 mm. The corresponding measurements 

 on the specimen of O. eremicola are 29.30, 17.20, 12.90 and 14 mm. 



Type. No. 23728, U. S. National Museum. 



The holotype is a female collected by M. A. Hanna of the U. 

 S. Biological Survey at a point 18 miles south of Dry Creek, 

 Montana, southwest of Lismas in Valley County. It is now in 

 the collection of the United States National Museum. 



If the superficial characters set forth above were the only basis 

 of separation, I should hardly care to give the Montana spec- 

 imen a name, but dissection of the genitalia shows that they 

 are different from those of the Wisconsin example of 0. eremicola. 

 The chitinized portions, in the female Osmoderma, are composed of 

 a pair of broad, irregularly oval pieces, nearly flat-bottomed with 

 reflexed margins, which may correspond -to the "inferior plates" 

 described and figured by Smith in his work on the genitafia of 

 Lachnosterna (Proc. U. S" N. M., XI, 1888, p. 4So,~et seq.). These 

 are similar in 0. eremicola 'and 0. montana, though not identical. 

 Opposed to these plates are four other chitinous structures, the 

 outer pair of which are probably the equivalent of Smith's "su- 

 perior plates," while the inner are likely the representatives of 

 what he calls the "pubic process." Comparison of these four 

 pieces in the two species of Osmoderma under discussion shows 

 that they are decidedly rougher and more deeply grooved in O. 

 montana. 



Incidentally, dissections were made of the male genitalia of 

 the American 0. eremicola and scabra, and of the European 0. 

 eremita. These are fully as characteristic in each instance as 

 those of our species of Lachnosterna and would indicate the pro- 

 priety of investigating these parts in describing new Scarabaeidae. 



Acknowledgments are due to Messrs. Schwarz and Barber of the 

 National Museum and McAtee of the Biological Survey, for fa- 

 cilitating the preceding studies. 



