lo University of Michigan 



several distinct types. Each segment may be of a single color, 

 without pattern, as in crytJirogastnun; the segment may be 

 apically dark or black as is albifroiis or chrysops; the segment 

 may be black at both apex and base with a pale mid-area, 

 making a three-banded segment, as in calendnhim ; or the 

 base may be pale, followed by a more or less distinct dark area, 

 followed by the pale ground color, which is in turn followed 

 by a distinct dark apex, thus making a four-banded segment. 

 This last pattern is the most common. In this pattern the sub- 

 basal dark area varies in intensity with age. It is superim- 

 posed on the pale basal color and shades out apically. To a 

 certain extent its development, by contrast, determines the 

 presence or absence of a pale basal ring. The apical black is 

 deeper and appears at an early age. The distinction between 

 the two black areas is possible even in niajiis, where the ex- 

 cessive development of the subbasal dark area has resulted in 

 segments 3-6 becoming chiefly black with pale basal rings. 



Geographical Distribution of Groups. — The two species 

 of group I are recorded from Southern Brazil or Brazil. Of 

 group 2, inacilaitiiin has been recorded from \'enezuela, and 

 ictericinii and mclaniiniui are now known from British Guiana; 

 all the others are known between parallels 10 ' and 35' S., 

 from southern and eastern Brazil, Paraguay, and Argentina. 

 Of group 3, icterops has been recorded from Brazil (Sant- 

 arem), A'enezuela. Ecuador and Peru. It seems possible there 

 have been some misidentifications. Four species have been 

 recorded south of the equator in western South America, 

 from Ecuador, Peru, and Bolivia. One species besides icterops 

 is known from Brazil and one species occurs in British Guiana. 

 The others occur to the west and north. Four species are 

 known from the ^^lagdalena River in Colombia; and one of 

 these and the remaining species of the group occur in Central 



