rii'.r.ixAi:: •iiir. (iknus i'ontia. 1159 



with a iiieilian groove whicli widens aiul deepens apically, making tlie wliolc se^iiunt 

 apponr doubly conk-al, the two sides exlendlm: shortly tioyoiid the niiddlo ; on a side view 

 ratluT sliMulrr, ciiuiil. bent somowbat downward ; the apical tlehl is transverse, slen- 

 der, holloweii in the ndddlc above, otherwise stral{;ht, the hooklets scattered over the 

 whole under surface of the apical edjie and above in tlie middle ; the hooklets are 

 rather distant, not lonj;, the stems slender, slijfht, curved .anil c<iual, exceplinf; near the 

 apical portion, which is greatly expanded and domed, curved over as in Pieris, but 

 with the sides of the expanded portion curved downwards and angulatcd. 



This genus is conunoii to liotli worlds and almost exclusively confined to 

 north temperate regions. In tiic Old World, however, it reappears in 

 southern Africa, a single species having long been known from the Cajje 

 of Good Hope. In the New World, on the other hand, it is replaced south 

 of the tropics bv a closely allied genus which is rather numerously repre- 

 sented. In liotii tlic Old and New A\'orld, Pontia stretches from ocean 

 to ocean. l)ut in liic fornu'r it is mucii more aliundant in species. In both 

 it extends from the 30th to the (iOth degrees of latitude. Only one species 

 reaches the confines of New England. 



The butterflies are scarcely larger than in Pieris, but have more pointed 

 fore wings. Like them, they are white but more extensively spotted with 

 dee]) brown : the fore wings have a broad bar at the tip of the cell and 

 midway between this and the outer border a widely interrupted transverse 

 series of similar but smaller spots ; the outer border, especially the upper 

 half, is also more or less distinctly margined with triangular (fre(|uently 

 confluent) spots seated in the interspaces; these occur more often in the 

 female than in the male. The hind wings have similar markings, at least 

 in tiie female, but they are much less distinct and the extra-mesial band is 

 generally continuous, narrow' and zigzag. Tlie.se markings are repeated, 

 generally less distinctly, beneath. 



The species vary in the number of their generations, some being single, 

 some double, and at least one — our eastern American species — triple 

 brooded. The spring generation of the polygoneutic species is always more 

 delicately marked than the later- butterflies and has sometimes been de- 

 scribed as specifically distinct. The insects winter in the chrysalis state. 



These butterflies differ greatly from those of Pieris in their rapid and 

 dashing flight; at least this is true of the Alpine species of Europe, which, 

 on this account, is very difficult to captiu-e, appearing suddenly and as 

 quickly passing out of reach. Meyer Diir writes that the flight of the most 

 common Eiu-opean species is just as restless and rapid ; and Doublcday 

 remarks : "daplidice and protodice have a quicker flight [than the species 

 of Pieris] and the latter [protodice], as far as I have observed, is never 

 seen playing in groups and ascending into the air as brassicae and raj)ac are 

 often seen to do" (Gen. diurn. Lep., i : 44) . The caterpillars feed singly on 

 Cruciferae, sometimes doing considerable damage to cidtivated plants, for 

 they are voracious feeders and mature rapidly. 



