MEIMOIES OF THE ^TATIONAL ACADEMY OF SCIENCES. 
43 
U. EVOLUTIOX OF LATER ADAPTATIOXAL CHARACTEiLS. 
1. Dorsal tubercles in- Stage II higher than before. 
2. The lateral dark band disappears in Stage IT. 
3. In Stage III the dorsal thoracic tubercles become nearly twice as long and thick as the 
rabdominal ones. 
4. The head is not banded in Stage lY. 
5. The tubercles brightest (pink or dark carmine) and most conspicnous in the last stage. 
G. A distinct iufraspiracnlar yellow line in Stage lY, and the suranal plate and anal legs lined 
with yellow, and the surface of the suranal plate and sides of the anal legs amber-colored. 
Family Cochliojmdkhe . — The slug-like larvie of the Bombycoid family Cochliopodidm, so 
remarkable from their snail-like mode of locomotion, their abdominalTegs being entirely atrophied, 
in their life history offer strong circumstantial evidence in favor of the primitive ra]»id acquisition 
of striking characteristics at the first molt. These larvm, as vre have elsewhere stated, are born 
without traces of' abdominal legs, are nearly colorless, and with bodies more cylindrical than in the 
full grown caterpillar. In the more specialized tul)erculated and ajuny genera Adoneta and T^mpre- 
tia (and probably Euclea) the tubercles are already differentiated in Stage I, much as in the last 
■stage, but otherwise the change from the first to the second stage is very great, so that the set of 
-congenital characters is very different from the assemblage of acquired characters, especially the 
addition of great numbers of bristles on the tubercles, and tlie gay varied colors and markings of 
the body. This sudden change, after but a single molt, shows that these characters are suddenly 
acquired. The larvm from being minute, pale-yellowish worms, hatching from almost invisible 
•scale-like transparent eggs, after the first molt undergo a striking change, the result of feeding in 
a more exi)osed situation and of consequent successful adaptation to prevent recognition on the 
l)art of hostile insects and birds. The armature of poisonous glandular spines and the development 
of bji’ight warning colors are evidently characters acquired late in larval life, when the creatures 
are large enough to attract notice. 
In illustration of the changes due to adaptation undergone by members of this family, I have 
selected the following examples, copied from a previous paper 
UECAinTULATIOX OF THE MORE SALIEXT ONTOGENETIC FEATURES OF EMPRETIA STIMULEA. 
A. COXGEXITAL FEATURES. 
1. The tubercles on the second and tliird thoracic and the first, seventh, and eighth abdominal 
segments three times the size of those on abdominal segments 2-G, these tubercles being already 
differentiated at birth and more markedly so than in Adoneta. 
2. Head not capable of being withdrawn into and concealed by the prothoracic segment. 
3. The tubercles each bear only three two-forked glandular setm. 
4. The body is more cylindrical than in the later stages and colorless. 
n. EVOLUTIOX OF ADAPTATIOXAL FEATURES. 
1. In Stage II the form and general colors of the full-fed larva are assumed. 
2, The tubercles are now armed with numerons poisonous spinules. 
NoTE.—Froin-svliafc we now know of the congenital as compared with the later acquired adaptational characters 
■of Cochliopods, it is evident that the latter are acquired at an earlier stage than in most other caterpillars. 
RECAPITULATION OF THE MORE SALIEN1’ ONTOGENETIC FEATURES OF ADONETA SPINULOIDES. 
A. COXGEXITAL FEATURES. 
1. 'No tubercles on the prothoracic segment. 
2. The dorsal tubercles on the second and third thoracic and first, fourth, seventh, and eighth 
abdominal segments double the size of those on the other segments, the tubercles being already 
differentiated at birth. 
^ Proceedings Aiiier. Philosophical Society, Phil, xxxi, pp. 83-108, 1893. 
