18 BULLETIN 15 7, U. S, NATIONAL MUSEUM 



general aspect. In the District no less than 14 northern butterflies 

 reach thoir extreme southern limit at sea level. These are as follows : 



Satyrodes eurydice. 

 Cercyonis alope marifinia. 

 Euphydryas phaeton. 

 Brcnthls myrvna. 

 Polygonia progne. 

 Argynnis aphrodite. 

 Sfrymon Ontario Ontario. 



Inoisalia augustinus. 

 Pyrgus centaureae. 

 Erynnis sassacus. 

 Atrytone pontiac. 

 Atrytone logan. 

 Poanes massasoit. 

 Atrytonopsis hianna. 



Some of these are not known from farther south, but most of them 

 range southwestward along or in the mountains to southwestern 

 Virginia or beyond. 



Whereas butterflies which in the north are generally distributed 

 become restricted south of the District to the mountains, butterflies 

 which are generally distributed in the south tend toward the north 

 to become more and more closely restricted to the coastal plain, along 

 which they extend northward into New Jersey, New York, and even 

 southern New England, and some of them also along both shores of 

 Chesapeake Bay to Baltimore or beyond. 



Thus there are recorded from the coast of New Jersey in the 

 vicinity of Cape May such southern species as Neonymfha fhocion^ 

 Cercyonis alope pegala, Dione vaniUae, Atlides halesus, Strynion 

 favonius, Gonmums yroteus^ Prenes panoquin, and Atrytone dion, 

 which do not occur in the vicinity of the District. Enodia port- 

 landia., which is generally distributed in North Carolina and in 

 southern Virginia, also occurs in this region, though not in the 

 District. It is interesting to note that in the region of Cape May 

 these southern species are found together with such characteristically 

 northern forms as BrentMs myrina^ B. hellona., Satyrodes ctiiydice, 

 and Strynion liparops. 



The relation of the District to the coastal plain is made clear by 

 observing the active and conspicuous Phoehis eubule and the scarcely 

 less noticeable Eurema niolppe. Both of these butterflies are readily 

 identified from a moving automobile. They are very common in all 

 the counties of Maryland bordering Chesapeake Bay, where they are 

 constantly seen along the sides of the road and in the fields. West 

 of the Patuxent River they rapidly become less common, and they 

 disappear sometime before the District line is reached. North of 

 the District they extend farther inland and are common, or at least 

 frequent, in the lower lands of Howard, Frederick, and Carroll 

 Counties, Md., and northeastward into Pennsylvania. Both species 

 are also common in the Maryland and Virginia counties along the 

 lower Potomac, and they are frequent as near the District as 

 Alexandria and Falls Church, Va. 



