DUiONKL'TlSM IX liUTTEKFLIES. 923 



fincmcnt Trifoliiim ; umong Rosacc.ie, Mospilus and Pirns in Europe and 

 .Spiraea in America ; and ot" otlicr families of poh})etaiou8 plants, Eschal- 

 lonia and Iledera in Europe and Cornus in America. Further we have 

 among the Gamopetalae, Viburnum, one of the Caprifoliaceac, in America ; 

 among Compositae, Cuscuta in Europe and Actinonicris and Verl)esina in 

 America, besides Diniorpiiantes, a cultivated tonn ; among Ericaceae, Erica 

 in Kuropc and Yaccinium in America ; further. Ilex in l)oth countries ; and 

 in conKnement, in America, Begonia, Salix and Asclcpias. With such a 

 list the caterpillars may surely be regarded as polyphagous. 



The eggs are of a very depressed echinoid shape and covered with tu- 

 bercles of diverse heights connected by delicate lines. 



The body of the juvenile larvae, which is subcylindrical l)ut tectiform, is 

 covered with high conical papillae from which emerge long, curved hairs 

 sweeping backward. The mature caterpillars are onisciform, about equally 

 and somewhat rapidly sloped in front and behind and have a similar ante- 

 rior and posterior cui-ve. They have rather distinctly marked segments, 

 are green in color with straight dorsal markings and oblique lateral stripes. 



The chrysalids are well rounded, of a dark green or fenaiginous color 

 with dusky markings, rather short and stout, the abdomen considerably 

 higher than the thorax. 



EXCURSUS XXXIII.— DIGONEUTISM IN BUTTERFLIES : 

 INTENSITY OF LIFE IN AMERICA. 



And now you went beside the flowers, with eyes 

 Earnest as bees, restless as butterflies. 



Leigh Hunt. — A Garden and Summer House. 



Is ALL plural brooded butterflies with an extensive distribution in lati- 

 tude, the number of generations varies with the length of the season, and 

 this will account for the apparent waste we often see as winter approaches, 

 for such changes must i)e gradual, and in intermediate districts irregular, 

 dependent upon the season. Where, as is sometimes the case, some 

 chrysalids of each brood live until the following spring, it manifestly 

 makes little difference how short the season may be, or how suddenly and 

 effectually any brood may be cut off; these chrysalids, and so the species, 

 will survive. That this feature is more common than is generally sup- 

 posed is shown by the increasing nmnbcr of proofs brought forward of 

 lethargic tendencies in caterpillars and of persistent torpor in many mid- 

 summer chrysalids. It is also indicated by the variation in the numerical 

 proportions of different broods ; the winter is the severest season, and 

 consequently the spring broods are ordinarily, and imder simple conditions 

 would always be, less numerous than the summer or autunm broods ; 

 generally the broods go on increasing in individuals as the season advances ; 



