107 



in which they are located, without any such peculiar reference to the 

 species of the same genus in other faunse, and so may also be well 

 termed species of replacement. It will thus be seen that any given 

 species may be a representative species when compared with one, and 

 an equivalent species when compared with another specific form. 



3'^. Complemental species, or those generically allied forms which 

 occupy the same geographical area, where, if I may so express it, the 

 specific material belonging to any one zoological fauna has been given 

 expression through more than one specific form. Examples have been 

 given sufficient to illustrate my meaning in regard to the first two 

 classes ; of the third, good examples will be found in Pieris Rapce 

 and Napas of Europe, which, in reference to one another, are comple- 

 mental species, while both together are representatives of our Pieris 

 oleracea. 



I place here three cuts exhibiting the marginal bands of the three 

 boreal American species of Colias, after the example of Menetries in 

 his catalogue, with descriptions appended. 



C. occidentalis. 



C. interior. 



C. labradorensis. 



Colias labradorensis (nov. sp.) 

 $ . Above, primaries lemon-yellow with a slight greenish tinge, 

 brighter than in C. Hyale, much as in C. Palceno ; marginal band 

 broad, black, dusted with yellowish scales ; the inner border irregu- 

 larly crenulated, parallel with the outer border, except near the costal 

 border, where with a full curve it is turned inward a little ; there is 

 also a slight turning in of the border just below the sub-median nervure ; 

 the fringe is of moderate width ; there are crowded black scales occu- 

 pying a small space at the lower portion of the base of the wing ; — 

 secondaries much the same color as the primaries, but having a very 

 slightly more greenish tinge ; the outer black band extends from mid- 

 way between the termination of the costal and upper branch of the sub- 

 costal nervures to midway between the termination of the sub-median 

 and lower branch of the median nervures, sometimes reaching the 

 former ; the band is of moderate breadth, with the inner border quite 

 regularly curved, sometimes slightly scalloped ; the base has many 

 black scales, giving a grimy appearance, not extending over a wide 

 space, but chiefly attaching to the median nervure. 



