1883.] PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 483 



others were haunting the woods, collected at the electric light and gave 

 many specimens for the purposes of study, also deserves my thanks. 

 Professor Riley, by his kind permission to use the Museum material, 

 and the suggestions offered, has materially added to the completew 

 of the paper. Finally Dr. Horn has my siucere thanks for the liber- 

 ality which induced him to place even unique types at my disposal foi 

 the study of the genitalia. I am happy to say that I did not in any 

 way injure a siugle specimen. In addition to the material from the 

 sources above enumerated, I have also received an I studied numerous 

 lots of specimens seut me by correspondents from all parts of the 

 United States, so that I believe that I have seen and carefully ex- 

 amined more specimens of Lachnosterna than even Dr. Horn in his 

 original study of the genus. 



Jn the course of our collections I first noted in specimens taken in 

 coitii a difference in the appearauce of the male genitalia. I am aware 

 that in a somewhat fragmentary way the genitalia of some genera of 

 Coleoptera have been studied in Europe, and that a few of our Scara- 

 bwidce also have been studied in connection with European species, but 

 I have made no exhaustive study of the literature of this subject. 

 In this country Dr. Horn has made use of the sexual structures in his 

 study of the species of Corphyra, but, so far as I am aware, no other 

 American author has made anything like a systematic attempt at their 

 study. 



The positive results seen by me in my studies of these organs in the 

 Lepidoptera led me to a careful examination of them in the species 

 here, in the hope that here might be the character by which the spe- 

 cies of the fusca group could be finally and satisfactorily separated. 

 The hope was realized even more fully than I had expected, and 

 the great differences found in the males led to an examination of 

 the females for correlated structures, which proved as distinctive as 

 those of the male, and which, so far as I am aware, have not been hith- 

 erto studied. 



A striking character in the males of many species is the remarkable 

 asymmetry of the organs, for which I can not find an entirely satisfactory 

 reason, and to which there seems to be no exact correlation of female 

 structures. I shall, further on, give the only explanation that I have 

 been able to find— whether sufficient or not I cau not at present be sure. 

 1 shall not endeavor to make any generalizations from the characters 

 described, fully realizing that it is much too soon for that. I simply 

 wish to add some information regarding the characters of the species, 

 and to record my ideas as to the standing of others. The characters 

 afforded by the genitalia of both male and female will, I am convinced, 

 be more and more used in the future to decide questions of specific iden- 

 tity. Perhaps it may be of interest to quote from Dr. Kraatz on tins 

 subject, Dr. Kraatz having worked considerably and well in this line. 

 He says (Deutsche Ent. Zeitschr., 1881, V. 25, p. 116): 



