ON THE N. A. SPECIES HITHERTO RECORDED. 57 



racterizes the Trypetidce. Moreover, their basal cells are smaller, 

 and the first longitudinal vein never has any bristles, but only a 

 short pubescence like that of the remainder of the surface of the 

 wing. 



The Lauxanidce and Sapromyzidce have still less relation to the 

 Trypetidce. They are readily distinguished from the Trypetidce by 

 their middle and hind tibiae being spurred with bristles before their 

 tip, and the outside of the tibia? bearing an erect bristle before the 

 tip ; the first longitudinal vein of the wings has no bristles, and 

 the end of the auxiliary vein never has the character peculiar to 

 that of the Trypetidce; the two posterior basal cells are small ; the 

 bristles on the anterior part of the lateral border of the front are 

 wanting ; in this respect we must not be deceived by the rows of 

 bristles, which run from the two bristles of the vertical border, 

 and which, being more scattered, extend farther anteriorly ; there 

 always exists only a single row of bristles, whereas the frontal bris- 

 tles in the Trypetidce always form two rows on each side, one of 

 which may be called the superior and interior, the other the inferior 

 and exterior. 



With the exception of the families mentioned above there is n 

 other so nearly allied to the Trypetidce, that it would be necessa 

 to point out its differences. 



5. On the N. A. species hitherto recorded. 



What has been written about the N. A. Trypetidce is very little in 

 amount. No species at all of the section Dacina has been described. 

 I have, however, seen the fragments of a fly captured in Cuba, 

 which belongs either to Dacus or to one of the nearest genera of 

 the Ortalidce; but as it is one of those osculating forms between 

 the two allied families, nothing can be said with certainty about its 

 systematic place before having seen a better preserved specimen. 



The N. A. Trypetce hitherto recorded are as follows : 



1. acidusa Walk., unknown to me, is either a relation of Tryp. suspensa 



and unicolor, the descriptions of which will be given hereafter, or 

 belongs to those species similar to them which have the fifth longi- 

 tudinal vein also beset with bristles. 



2. albiscutellata Harr. must be omitted, since it is undescribed. 



3. antillarum Macq. belongs to the Ortalidas, being erroneously placed 



by Macquart in Urophora, a genus of the Tiypetina. 



4. arcuata Walk, differs in nothing from Tryp. flexa Wied. and belongs 



to the Ortalidse. 



