44 
MEMOIES OF THE XATIOIS'AL ACADEMY OF SCIENCES. 
3. The prothoracic segment not yet forming a hood, the head not retracted within it so readily 
as in the last stages. 
4. The tubercles each bear only three three-forked glandular setm. 
5. The segments are more distinct than in the later stages. 
6. The body is pearly white, slightly puridish on the back. 
B. EVOLUTION OF ADAPTATIOXAL FEATURES. 
1. The body in Stage II assumes nearly the form and colors of the last stage, the tubercles^ 
being armed with numerous spines and some of them tinted with red.- 
2. In Stage III the colors and appearance of the full-fed larva are assumed. 
ilECAPITULATION OF THE MORE SALIENT ONTOGENETIC FEATURES OF LITHACODIA FASCIOLA,. 
A. congenital features. 
1. The larva is hatched without any tubercles. 
2. The glandular hairs are of the same size and shape in the dorsal and subdorsal rows, being 
short, with a tine at the middle and forked at the truncated end. 
3. The body is more cylindrical than in the last stages and not skiff- like, and the segments are- 
distinct and simple. 
4. The body is at first colorless. 
B. evolution of adaptational features. 
1. The body becomes skiff-like when 5.5 mm. in length. 
2. The color is pea green, like that of the leaf it feeds on, with straw-yellowish marks and spots.. 
3. The skin becomes rough and granulated and the plateau distinctly marked in Stage III 
or IV. 
4. In the last stage the minute spines disappear. 
VI.— GEOGRAPHICAL DISTRIBUTION OF THE AMERICAN N0T0D0NTID.€. 
MAPS I-X. 
The Lepidoptera are, as regards the higher groups, from the Bombyces to the butterflies, very 
largely tropical, the number of species diminishing as we pass from the equator to the poles. 
Mr. Wallace^ states that the distribution of butterflies corresponds generally with that of 
birds in showing a primary division of the earth into eastern and western rather than into 
northern and southern lauds. From his studies on the distribution of butterflies and ‘^Sphingina” 
(including, however, the xEgeriidm, Oastniidm, Agaristidjc, Zygmnidse, Urauiidm), he concludes 
that “the neotropical region is by far the richest and most peculiar.” 
The Zygjcnidfe or day-flying moths are usually restricted to the Tropics, as we have seen in a 
striking manner when descending from the temperate zone of Mexico to Cordova, which is 
situated in the tropical zone (tierra caliente), and it is easy to recognize the fact that our United 
States species of this family have been derived from the tropical regions of Central and South 
America and the Antilles. 
It would be premature for us to enter iuto even a provisioual account of the distribution 
of tlie Bombyces as a whole until we have comideted our survey of the members of the entire- 
superfamily, and oui’ remarks at present will be therefore confined to the Xotodoutidm. 
It may, however, be well to bear in mind some general results which are quite obvious to oue 
who has paid even slight attention to the Bombycine moths. 
While the i^otodoutidm appear to be both tropical and temperate forms, though it should be 
borueiii mind that we know but little of the tropical forms, and few species are known from India- 
or southern Asia in general, certain other families are largely tropical. 
^The Geographical Distribution of Animals, 1876, ii, p. 483. 
