F. R. COLE y 



considerably. The fork of the third longitudinal vein is present, 

 but in one species from North America (0. loewi) the lower branch 

 does not reach the wing margin. In 0. schivarzi new species, from 

 Cuba, this is not the case, but the vein from the outer first basal is 

 only a stump. 



The genus AstomeUa, which does not occur in North America, is 

 intermediate between Thyllis and Pterodontia; the unforked 

 third longitudinal vein can be traced; the closed fourth posteripr 

 cell remains (actually the third), and a fifth longitudinal fork, but 

 the second veinlet from the discal has disappeared and the num- 

 ber of posterior cells has been reduced. It becomes clear that 

 the wide open space at the wing tip is the first posterior and not a 

 submarginal cell. 



Pterodontia (Plate I, figs. 6 and 7) shows a great change in the 

 development of the third (discal) vein. The second longitudinal 

 vein curves up into an enlargement of the costa. P. ancdis shows 

 the continued presence of two discal cross-veins, and also shows 

 that the so-called outer first basal cell has merged with the discal 

 cell, thus the upper branch of the fourth vein has disappeared, 

 but the upper veinlet of the discal cell remains, the lower branch 

 of the fourth longitudinal bends sharply downwards and meets the 

 upper branch of the fifth vein, going to the wing margin. In P. 

 analis there are three posterior cells and in P. flavipes two. 



In Og codes (Plate I, fig. 2) the discal cross-vein is still apparent, 

 but is very faint. The first basal cell is much longer, and thus 

 the discal cell is much farther from the base of the wing, and, con- 

 sequently, as the supernumerary discal cross-vein is not required 

 it has disappeared. The shape of the anal cell indicates a de- 

 graded form of AstomeUa as Verrall noticed. The outer cross- 

 vein has disappeared, so the lower one of the three vagus veins 

 between the third vein and the lower branch of the fifth longi- 

 tudinal would be a branch of the fourth longitudinal. 



Philopota (Plate I, fig. 5), one species of which {truquii Bellardi) 

 was described from Mexico, shows the auxiliar}^, first and second 

 veins clearly, but the next (incomplete) vein may be the upper 

 branch of the third vein, and if so the discal cross-vein is absent. 

 The apparent cross-vein will be (as in Acrocera) the 1)eginning of 

 the upper branch of the fourth longitudinal, and there arc two 

 rather undefined V)asal cells. 



TRANS. AM. ENT. SOC, XLV. 



