i6 E. B. Williamson 



2i'. Wings with the entire niiembrane suffused with yellowish crnccipriiiiis. 



22 (i6'). Abdomen slightly constricted at segment 3, the space between the lateral 



and ventral carinae narrowed at the level of the transverse carina to about 

 one-half or less the maximum width between them posterior to this point. ...23. 



22'. Abdomen not constricted at segment 3, the space between the lateral and ventral 

 carinas slightly or not narrowed at the level of the transverse carina 24. 



23 (22). Smaller, hind wing 43-46, venation less complex, two rows of cells between 



the anal loop and the hind margin of the wing. Cuba and the Bahamas, .crcagris. 



23'. Larger, hind wing 55, venation more complex, three rows of cells between the anal 

 loop and the hind margin of the wing. South America lit oralis. 



24 (22'). Wings hyaline or uniformly tinged nervosa. 



24'. Wings with a distinct dark stripe near the costal border 25. 



25 (24'). Wing membrane suffused with yellowish or brownish, the costal stripe 



bounded posteriorly by R croceipennis. 



25'. Wings hyaline except the costal stripe 26. 



26 (25'). Costal color yellowish, darker to brownish at base, bounded posteriorly 



by R bifida. 



26'. Costal color darker, browner and wider, bounded posteriorly by M. . .interioris. 



27(6'). Colored liasal wing area reduced, occupying less than half the median space 

 and bounded posteriorly by A ; T-spot on frons well marked. Male with the 

 ventral carina on segment 2 with few to no teeth anterior to the point of 

 convergence and a few posterior to the same point and with seven or eight 

 denticles on the auricle gracilis. 



27'. Colored basal wing area extensive, occupying all or nearly all the median space 

 and extending posteriorly beyond A, especially in the hind wing; frons above 

 black or obscure, no evident T-spot. Male with the ventral carina on segment 2 

 with a row of ten or more teeth anterior to the point of convergence and none 

 posterior to this point, and with only three or four denticles on the auricle 

 membranalis. 



Discussion of Species^ 



Triacanthagyna scptiina Selys 

 6, 7, 10 (female is ditzleri), li, 12, 23, 25, 26, 36, 40. 



Abdomen male 38-45, female 42-48; hind wing male 34-41, female 37-43; 

 superior appendage male 4.2-5, female 5-5.2; stigma front wing 3-3.5. 



Dr. Calvert has called attention to the variation in the number of cells 

 in the anal triangle in this species. And equally surprising is the variation in 

 both sexes in the number of rows of cells between M^ and IMspl in the hind 

 wing and the number of cells in the anterior row of cells in the anal loop. 

 Of fourteen males from Puerto Barrios, six have four rows between M^ and 

 Mspl, seven have three, and one has four on one side, three on the other; of 

 twelve females from the same locality nine have four rows and three have 

 three rows. Moreover the four-rowed condition is not confined to specimens 



' Numbers following each species refer to the citations in the bibliography. 



