8 MEMOIRS OF TlIK NATIONAL ACADEMY OF SCIENCES. 



luiiiips. :iiul spines, and thus nioiv iitKtuiforni. At the same time the yellow and whitish stripes 

 and pink blotches become indicated at an earlier stage than usual, as it' the aim were to adapt 

 the caterpillar to the hues of the ribs and parallel f^reenish and yellowish lines and reddish spots 

 of the leaf on which it feeds. 



A variety of Jfderocampa mnnteo (Monogr., PL XXIX. tigs. 5. :ui), with a ground color 

 like the green of birch leaves, is beautifully colored with two subdorsal white lines, which in the 

 third and sixth abdominal segments expand so as to contain a conspicuous deep blood-red spot 

 on each side: there is also a lateral yellow spiracular line. As I state in the monograph (p. :22S): 

 "It is plainly derived from normal v/^r?/*/'-". and is adapted for existence on the pale yellowish 

 gre(Mi underside of the birch leaf, while the deep blood-red spots are similar in color to those of 

 the birch twigs or leafstalks." 



The evolution of the red dorsal spots on Ileterucainpa (luttivitta is shown on PI. XXXI. In 

 stage I there are no lines, the bodj- being of a uniform reddish hue, and armed with nine pairs of 

 liorns, those of the first pair being really collossal in size, like the antlers of a stag; but after 

 casting its skin, when the horns are all dropped, only slight vestiges of the prothoracic pair 

 surviving, two parallel paler reddish lines arise and extend along the sides of the body. These 

 lines widen, become dittusc and are lost or at least the lower line, just before the next ecdysis, 

 leaving two medio-dorsal closely contiguous lines. These two lines after the second molt (stage 

 III) become broken up into large deep blood-red patches on the thoracic and third, fourth, and 

 seventh and eighth abdominal segments. On the prothoracic segment the two lines diverge, 

 })eing forked, and this forked line persists to the end of stage IV. Already in stage III there 

 are the indications of the three short lateral oblique lines, which are more fully developed in tlie 

 fourth stage and continue to the end of larval life. They are deep red and are shaded above with 

 white. With little doubt the dorsal red spots of the young larva of //. innnteo (PI. XXIX, 

 fig. 2, 2a) arise in the same way, the spots being on the same segments, while the forked liright 

 red thoracic line is like that of // guttlviiUi. 



In // hlundata also the freshly hatched larva is red. the green hue appearing after the worm 

 has begun to eat. In this beautiful insect toward the end of larval life it is readily seen from 

 PI. XXXII that it is amply "•obliterated" by its coloration, and stands in no need of horns, 

 which are, rather late in life, however, discarded. 



The caterpillar when at rest usually stands on the inidril) on the undi-rsidc of the leaf, where 

 its green and white shades and lines well protect it from the prying eyes of insectivorous birds. 



The figures of this species on PI. XXXII well illustrate the wonderfully close resemblance 

 in color and markings of this caterpillar to the hues of the leaf and the rust-brown and darker 

 brown blotches on either surface of the leaves, in whatever position the larva assumes. 



ORIGIN OF THE LINKS AND SPOTS IN DATANA. 



Orlijin <,f the iransvcrse spots vf Jhitanit iiiojar from UnKjUiidhtdf .sY/vy/^.v. -The larvte of all 

 the species of Datana, with the exception of D. vuijoi\ arclongituditialiy striped. The ground 

 color of the body in all the species is usually some shade of reddish brown or dark brown, 

 while the stripes are reddish, yellowish, or whitish, according to the species, as may be seen by 

 reference to Pis. X to XIV of my monograph. Part I. As is well known, these conspicuously 

 marked caterpillars feed in an exposed manner in clusters on the apple and certain forest trees 

 and shrubs, assuming grotes(iue attitudes; it is most probable, though no experiments have 

 been made with them, that these caterpillars are distasteful to birds, since the European Pijgcvra 

 Im-ipluda is distasteful to lizards (Poulton). These larviC are abundant, there are niuiieroiis 

 species, and the genus in point of numbers of individuals as well as species is a successful one. 



In my work I described in some detail the differences in the markings of the larvw at different 

 stages, but failed to draw, or rather deferred to a later occasion, some conclusions as to the mode 

 of origin of the lines, and particularly the transverse series of spots of D. ludjor. 



In J), major the larva has taken a wide departure from the style of markings of its congeners. 

 As may be seen in I'l. Nil, Part 1, the young larva, up to the time when it is about half grown, 



