II. 



ON THE NORTH AMERICAN TRTRETIDAE. 



1. Extent of the family Trypetid^e. 



In stating that the family of Trypetidce comprises the genera 

 Trypeta Meig. and Dacus Wied. we define its limits as exactly as 

 is possible before having developed its character. 



The genus Trypeta was founded by Meigen in Illigerh Magazine 

 II, 277, 94. Shortly after, the same genus was published in 

 Schrank's Mama Boica under the name of Trupanea, and still 

 later, it appeared in Latreille's writings, in a more vague circum- 

 scription, under that of Tephritis. 



The number of species belonging to it has so much increased 

 since the time of its creation, and so considerable differences in 

 their organization have been observed, that not only the limits of 

 •the genus have become a little uncertain, but also the necessity of 

 a division into smaller genera was felt, and more than one attempt 

 to satisfy this want has been made. 



The first attempt, abortive both from the choice of unfit charac- 

 ters and from the vagueness of the observations used as foundation 

 for the characters, was made by Robineau Desvoidy, who distri- 

 buted the species known to him among the genera Ensina, Stylia, 

 Oxyna, Oxyphora, Terellia, Forellia, Xyphosia, Sitaria, Orellia, 

 Tephritis, Urophora, Aciura, Prionella, Sphenella, Urellia, Acinia, 

 and Nceeta, to which his genera Acidia and Strauzia must be also 

 added. 



Subsequently Macquart reunited these genera into five : Uropho- 

 ra, Terellia, Tephritis, Acinia, and Ensina, to which he added the 

 genus Ceratitis M'Leay, which he had previously described himself 

 under the name of Petalophora. Later, in the "Dipteres exotiques," 

 he added Acanthoneura, Campylocera, Meracantha, Toxura, and 

 Epicerella; the four last, however, if we may depend on his de- 

 scriptions and figures, must be placed among the Ortalidce. 



Mr. Walker, in the " List of the Diptera of the British Museum, " 

 adopted the genera of R. Desvoidy, after modifying the characters 

 4 



