10 ILLINOIS BIOLOGICAL MONOGRAPHS [404 



In the above list species occurring in two are counted in both. So 

 far as practicable these pilosity groups have been considered in working 

 up, arranging, and discussing the patterns. 



Considerable change has been made in the nomenclature and arrange- 

 ment of species in the Genera Insectorum as compared with Doctor 

 Horn's Index. The paper had progressed so far with the Index as a 

 basis that it was thought not to be practicable to change it to agree with 

 the newer work. 



The extensive collection of North American species belong to the 

 first group in Horn's series for the Nearctic region. This group includes 

 tranquebarica and will be referred to as the Tranquebarica Group. These 

 are characterized as follows: The four anterior trochanters have fixed 

 hairs, cheeks naked, or with isolated hairs, clipeus often hairy. Frons 

 with discoidal or supraorbital hairs; median portion of the frons never 

 proportionately supplied with more or less short, close lying, downward 

 directed hairs ; frons never hairy above the antennal insertion. The disc 

 of the middle frons is often hollowed out or sharply separated from the 

 fore frons by its steepness. The first antennal segment is often thickly 

 covered with outstanding hairs. The pronotum has at least rudiment- 

 ary hairs, often circumdiscally and discally hairy ; hairs often long and 

 fine and never decumbent except when very numerous ; free anterior and 

 posterior border of the pronotum not hairy. The prosternum is always 

 naked. The lateral portion of the breast is always thickly covered with 

 hairs. The hind border of the femur and sometimes the foreborder also 

 covered with fine short decumbent hairs ; hook-formed hairs never pres- 

 ent; hairs on the hip and superorbital border most numerous. This 

 group stands in close relation to the European group to which campestris 

 belongs. The main group includes formosa* venusta, Umbata, purpurea* 

 ancosisconensis, duodecemguttata* hirticollis* latesignata, tranquebar- 

 ica* tenuicincta, bellissima, longilabris, eureka, oregona, senilis, willi- 

 stoni, fulgida, pulclira, pimeriana, scutellaris* In addition to this, 

 collections were made of C. sexguttata which stands in a group by itself. 

 Those starred were studied especially. Collections of these species 

 representing complete catches were supplied by C. S. Brimley, E. G. 

 Smyth, C. A. Frost, L. H. Joutel, Kev. J. C. Warren, and Dr. C. F. 

 Adams. Collections were made by the 'writer in various parts of the 

 United States. 



The species about Chicago, especially scuteUaris, were collected 

 through the year from the same locality with a view to getting the 

 seasonal variation of the species and any variation from generation to 

 generation. 



