DISTRIBUTION OF BUTTERFLIES IN THE NEW WORLD 335 



The Dismorphiinae comprise a small group that may not be 

 derived from the Pieridae. Its range is wholly tropical, with a slightly 

 greater extension to the south than to the north of the tropics. Of 

 the two genera, Dismorphia has the same distribution as the sub- 

 family and P seudopieris is restricted to a range from 15° N. Lat. to 

 15° S. Lat. 



Danaidae (Figs. 5-7) 



The Danaidae comprise thirty-five genera, all but one of which 

 are restricted, or almost confined, to ranges between the Tropics of 

 Cancer and Capricorn. The only genus not so restricted is Danais, 

 one species of which extends its range annually to latitudes of 55° N. 

 and 55° S. by seasonal migration. In addition, this species manages 

 to remain at home at latitudes up to 40° N. and 30° S. The distribu- 

 tional range of the family as a whole forms a pyramidal histogram 

 with the median point centered at about 10° N. of the equator, 

 rather than being centrally placed across the tropics. Higher eleva- 

 tions are inhabited north of the equator than southward, but it is 

 possible that this apparent phenomenon is due to the lack of suffi- 

 cient information for the humid region on the east side of the Andes 

 south of the equator. 



The Lycoreinae with two genera are equatorial at low elevations. 

 The Mechanitinae are also equatorial but extend to 25° S. Lat. 

 This is a very large subfamily ranging from sea level to 2,000 meters. 

 All thirty genera are found within this range; some occupy the 

 whole range, others only a narrow segment. For example, Athesis 

 occupies a range from 10° N. Lat. to 5° S. Lat. at elevations of only 

 1,000 to 2,000 meters. Sais is found only from 5° N. Lat. to 0°. No 

 reasons for the restricted ranges of some of these genera are apparent 

 from the histograms. A great proportion of genera occupy the area 

 from 10° or 15° N. Lat. to 10° or 15° S. Lat., although there are no 

 geographic barriers in these regions to hinder their expansion to 20° 

 in either direction. The family as a whole should be considered as 

 one of entirely tropical origin, for no representative lives perma- 

 nently in cold regions. 



Morphidae (Fig. 7) 



The Morphidae are represented by one genus (Morpho), which is 

 entirely equatorial though extending to considerable elevations (up 



