1978] 
Shapiro — Pierid Butterflies 
283 
SCHMALHAUSEN, I. I. 
1949. Factors of Evolution. Blakiston, Philadelphia. 
Shapiro, A. M. 
1968. Photoperiodic induction of vernal phenotype in Pieris protodice Bois- 
duval & LeConte. Wasmann J. Biol. 26: 137-149. 
1973. Photoperiodic control of seasonal polyphenism in Pieris Occident alis 
Reakirt. Wasmann J. Biol. 31: 291-299. 
1976. Seasonal polyphenism. Evol. Biol. 9: 259-333. 
1977. Phenotypic induction in Pieris napi L.: role of temperature and photo- 
period in a coastal California population. Ecol. Ent. 2: 219-224. 
SUFFERT, F. 
1924. Bestimmungsfaktoren des Zeichnungsmuster beim Saisondimorphismus 
von Araschnia levana/ prorsa. Biol. Zentralb. 44: 173-188. 
Watt, W. B. 
1969. Adaptive significance of pigment polymorphisms in Colias butterflies. 
II. Thermoregulation and photoperiodically controlled melanin varia- 
tion in Colias eurytheme. Proc. Nat. Acad. Sci. USA 63: 767-774. 
