BUTTERFLIES — HERRERA AND FIELD " 499 



wings above almost always entirely white. In a very few specimens 

 there is some black scaling along the veins at the outer margin and a 

 submarginal series of small sagittate markings. Wings below with 

 hindwing and apex of forewing yellow. Costal margin of hindwing 

 and interspace below cell at base of wing darker yellow to pale orange. 

 Hindwing v.ith cell divided in the middle by a bar of dark brown 

 that is itself divided by a thin line of yellow and with a distinct white 

 spot on lower discocellular vein. Veins on hindwing white entirely 

 outlined on both sides with dark brown, gray, or black. Veins in 

 apex of forewing white to yellow outlined on both sides with this 

 same dark color for a short distance inward but not reaching the 

 submarginal row of sagittate markings. These sagittate markmgs 

 are almost always present on forewing and hindwing, but on the latter 

 they occasionally may be only wealdy indicated. 



Length of forewing, 20-29 mm. (average, 26.1 mm.). 



Male genitalia as illustrated (figs. 33, 47). Differing from T. mi- 

 crodice and T. vanvolxemii in having the distal end of the aedeagus com- 

 pressed entu^ely laterally instead of approximately dorsoventrally. 

 Thus a lateral view of the aedeagus of mercedis has the nearly exact 

 appearance of a ventral view of the other two species. The genitalia 

 of 11 males were studied. 



Female: Plate 5, figiu-es 18-18b. Head as in the male with outer 

 siu:"faces of palpi white and scales behind eyes white. Wings above 

 with ground color white, sometimes suffused with pale yellow, espe- 

 ciall}^ on the hindwing. Dark brown to black markings as illustrated, 

 much more extensive than in the male and similar to female 

 vanvolxemii. However, on the forewing the discocellular bar is much 

 more narrow, the submarginal sagittate markings on both wings are 

 smaller, separate and not nearly so confluent, and more sharply 

 sagittate along the outer edges than in vanvolxemii. Wings below 

 with ground color of hindwing and of apex of forewing more dis- 

 tinctly yellow than in vanvolxemii. Hindwing with cell divided in 

 the middle by a bar of dark brown that is itself divided by a thin line 

 of yellow, and with costal margin and sometimes interspace below 

 cell at the base darker yellow to pale orange. Hindwing with a 

 distinct white spot on lower discocellular vein and with veins white 

 outlined along either side by dark brown or black clear to the base. 

 Veins along outer margin of forewing white bordered by dark brown 

 or black about one-half the distance toward the submarginal sagittate 

 markings and thus dift'ering from vanvolxemii where these markings 

 extend clear through the submarginal band at least along some of the 

 veins. Discocellular dark brown bar on forewing much narrower 

 than in vanvolxemii and submarginal sagittate markings on both 

 wings entirely separate and much smaller than in that species 



472317—59 3 



