322 LEPIDOPTERA OF NORTH AMERICA. 



12. P. tau Scudder. Pr. Bost. Soc. N. H. VIII, Sept. 1861, 183. 



Above, pure white ; costal border of primaries with a broad 

 black band, suddenly bending downwards and outwards, and fol- 

 lowing the discal nervule to its uttermost extremity, forming, with 

 the black body, an elegantly formed T ; this band has a white 

 streak in it at the base ; beyond the costal band, and connected 

 with it by the black edge of the costal border, is a large apical 

 spot, the inner edge of which runs parallel to the outer edge of the 

 extension of the costal band, till it reaches the first inferior ner- 

 vule, when it curves towards the base a short way, and again ex- 

 tending downwards, with an incurved border, reaches the second 

 inferior nervule, where it is rather abruptly broken ; this spot has 

 three or four, sometimes five white, unequal, oval, sometimes round 

 spots, the largest nearest the apex ; some blackish scales follow 

 the principal nervures of the secondaries for a short distance, and 

 the tips of the nervures are sometimes black, otherwise there are 

 no markings on the secondaries of the male, except the dusky re- 

 flection of the markings of the lower surface, which the transpa- 

 rency of the wing allows ; the female, however, repeats slightly at 

 the outer angle the markings of the lower surface. 



Beneath, pure white ; the markings of the upper surface of the 

 primaries are repeated, with the white spots and streaks slightly 

 enlarged and increased ; the nervures of the secondaries are all 

 narrowly bordered with blackish scales, which expand at the tips ; 

 commencing at the termination of the first superior nervule, a sub- 

 marginal narrow band approximately follows the curve of the 

 margin, is beut at the third superior nervule, and extends to the 

 inner angle. 



Labial palpi with mingled black and white hairs; antennas 

 black, with white scales scattered irregularly over the sides and 

 under surface, as far as the club. Body black, with whitish hairs, 

 especially below. The wings expand two inches. 



It represents in Washington Territory the P. sisimbrii Boisd. 

 of California. A large number of specimens are in the Museum 

 of Comparative Zoology, obtained by Mr. A. Agassiz at the Gulf 

 of Georgia. 



The distinction I have made between males and females in the 

 foregoing descriptions, is founded upon characters which I first 

 noticed by comparing together the two sexes of P. protodice, a 

 species whose sexes have been known for a long time, and which 



