MELANISM AND AMIINISM. 1285 



The transt'oriiKitions of scvcnil species are well known ; the insects 

 hihcrniite as chrysalids and are single or multiple brooded, according to 

 latitude. The eggs, which iiatch in a little more than a week, are laid 

 singly and the caterpillars live in solitude on a great varictv of angiosper- 

 nions i)lants : they spin a silken weh n\ cr a whole leaf an<l draw the sides 

 together, making a trough in wiiicli they lie when not feeding. The chry- 

 salids hang for ahont a fortnigiit in midsummer. The butterflies frequently 

 congregate in great numbers. 



The eggs closely resemble those of Kuphoeades in general form and 

 appearance. They are not snicarcd with any coating. 



In the juvenile larvae the second thoracic segment is the largest and 

 behind this the body tapers regularly and is covered with a few longi- 

 tudinal rows of warts and tubercles mostly provided with hairs, those 

 on the tid)crcles often clubbed at the tip. The mature caterpillars closely 

 resemble in form and markings those of Euphoeades, but have a trans- 

 verse, yellow stripe bordered with black at the incisure between the first and 

 second abdominal segments. 



The chrysalids. however, differ considerably from those of Euphoeades, 

 approaching rather those of Papilio. They are nearly straight with very 

 little fulness to the attingent edges of the wings ; on the inesonotum is a 

 small, tuberculate prominence facing forward ; similar parallel ocellar 

 prominences occur on the head, and a row of small, laterodorsal tuber- 

 cles on the abdomen. It is generally gray-brown in color, sometimes 

 green, always streaked with blackish, and resembles a rough bit of bark. 



EXCURSUS XLIX.— MELANISM AND ALBINISM. 



And whatso olso of \crtue good or ill 

 Grewe in this (ianlin. fctclit from farreaway, 

 Of <'V<'ri« one lie talics, and tastes at will. 

 And on their pleasures greedily doth pray. 

 Then when he hath botli plaid, and fed his fill, 

 In the warm Sunne he doth hiinselfe embay, 

 Anii there him rests in riotous sullisunnce 

 Of all liis gladfulness, and kingly joynnnce. 



Spenser. — Muiopotmos, 



Variation in the coloring of butterflies sometimes shows a definite ten- 

 dency, repeated in widely separated groups. Instances of this sort are 

 melanism or melanochroism and ali)inism, the former terms expressing a 

 tendency of the markings of the upper surface of the butterfly to become 

 wholly or almost wholly black, the latter of the lighter colors, which may 

 be normally vivid, to appear as if bleached. 



As instances of melanochroism we have in our own fauna two striking ex- 

 amples, one the female of Jasoniades glaucus, where many of this sex show 

 a tendency, farther and farther toward the south, to become altogether 



