NORTH AMERICAN I>EI'IDOPTKRA. 107 



'rhefenuhnn is a single spine in both sexes. In tlie male it rises 

 from a rounded base, while in the female the base is flattened and 

 the organ seems to consist of three or four spines fused together and 

 continuing to the end as one. I have found only one or two instances 

 where there 'was a real division of these i)arts. 



Venation. — The venatioit. is exceedingly variable in the different 

 species. The fore wings have 11, 10, or 9 veins. Vein 7 is always 

 absent. 



In the lO-veined species the additional vein lost is sometimes one 

 of the subcostal series, then vein 8, and sometimes one of the median 

 series, and then vein 5, as it seems to me. In the 9-veined species a 

 vein is lost from both of the subcostal and lower median series. In 

 the family, vein 9 is always stemmed on 8. Vein 6 is always near 

 or at the anterior angle of the cell in American species, never stemmed 

 with 8, and o, 4 and 5 are near the posterior angle, with 2 rarely 

 near, generally somewhat distant. Vein 1 is never furcate near the 

 base, and vein 12 is always separate from the cell. In all cases the 

 cell is closed, though often the cross-vein is weak. There is very 

 little variation in the length of the cell as compared with the length 

 of the wing and little more in its breadth. 



The hind wings have 8, 7, or 6 veins, with three internal veins 

 counted as one. When there are 7 veins only, the one lost is gen- 

 erally of the lower median series, and when G veins only, generally 

 vein 8 as well ; rarely the loss is of two veins of the submedian 

 series. The internal veins are never furcate at the base ; vein 2 is 

 near the posterior angle, or quite far removed ; veins o, 4 and 5 are 

 at or near the posterior angle, and veins 6, 7 and 8 at or near the 

 anterior angle of the cell. Vein 8 always merges with the anterior 

 margin of the cell, and 6 is sometimes in part stenuued with 7. 

 There is considerable vai'iation in the length of the cell as c(jinpared 

 with the wing. Generally about one-half the wing, it is rarely very 

 short, in one case not exceeding one-fifth the wing length. The cell 

 itself is generally part open, the cross-vein rarely distinct. The 

 cross-vein posteriorly runs often into vein 5, the submedian vein into 

 o and 4, thus leaving a narrow opening between. 



In almost all these veins of both wings there is considerable varia- 

 tion in position. In the fore wings 4 and 5 may be stemmed or 

 .separate ; 10 separate, or stemmed with 8 and 9. Very rarely 3 is 

 stemmed with 4 and 5. In the hind wings 4 and o are stemmed or 

 separate, 3 sometimes stenuued with 4 and 5, and 7 and 8 uuiv be 



