DISTRIBUTION OF BUTTERFLIES IN THE NEW WORLD 329 



family, being exceeded by the family only in the northern parts of 

 the range and only by the genus Parnassius. The latitudinal range 

 is greater in the north than the south, going to 65° N. and to only 

 35° S. Also, the elevations attained are higher in the north than in 

 the south: to 4,000 meters at about 35° N. Lat. and to only 1,000 

 meters at 35° S. Lat.; to 3,000 meters at 10° to 20° N. Lat. but to 

 only 2,000 meters at 10° to 20° S. Lat. The distribution of the genus 

 has a northern skew, because, as shall be seen below, some groups of 

 northern origin are superimposed in the north on groups of tropical 

 or equatorial origin. 



The genus is subdivided into three natural groups, the Aristo- 

 lochia, the Fluted, and the Kite Papilios. The Aristolochia group, 

 extending from 42° N. Lat. to 35° S. Lat. has a tropical range, ex- 

 tending into the non-equatorial regions only where winter tempera- 

 tures are not too cold and long. Elevations to 2,000 meters are 

 attained in the equatorial range. Of two sections of the Aristolochia 

 Papilios, only one, comprising the Polydamus group, extends north 

 of the equatorial area more than 5°. The other section (A) is tropi- 

 cal, but extends farther south (35° S.) than north (25° N.). This 

 section consists of three natural groups {Ascanius, Aeneas, and 

 Ly Sander), which have about the same range in the equatorial region. 



The Fluted Papilios have nearly the same range as the genus 

 itself, and comprise both northern and tropical members. The 

 species groups considered here are clearly seen on the chart to be 

 divisible into two parts, a northern part consisting of the Machaon 

 and Glaucus groups and an equatorial part consisting of the re- 

 maining six groups. The Machaon and Glaiccus groups extend to 

 65° N. Lat. and the Machaon group reaches 3,000-4,000 meters in 

 elevation in the region of 35-40° N. Lat. Both groups extend into 

 the equatorial regions at middle elevations (2,000-4,000 meters) 

 and the Machaon group extends as far as 10° S. Lat. in the Andes. 

 The Glaucus group does not reach across the barrier presented by the 

 Panamanian isthmus. Of the tropical groups, only Thoas extends 

 much north of the Tropic of Cancer and then only to 42° N. Lat. 

 Except for the Homerus group, the others are strictly equatorial 

 and tropical, not exceeding 1,000 meters in elevation. The Homerus 

 group ranges up to 3,000 meters in the equatorial belt. 



The equatorial Kite Papilios are represented north of the Tropic 

 of Cancer only by the Marcellus group. The Lysithiaus and Thyastes 



