ME:\i()n!s OF THE national academy of sciences. 43 



I!. EVOIA'TIOX 0I>' LATHIt A 1>A I'TATII IXAI, III A ItACTEUS. 



1. Dorsal tubercles in Stage II higher than before. 



2. Tlie lateral dark band disappears in Stage II. 



3. In Stage III the dorsal tlioracic tubercles become nearly twice as long and thick as the 

 abdominal ones. 



4. The head is not ))anded in Stage IV. 



5. The tubercles brightest (pink or dark carmine) and most conspicuous in the last stage. 



(>. A distinct infraspiracular yellow line in Stage IV, and the siuanal plate and anal legs lined 

 with yellow, and the surface of the suraual plate and sides of the anal legs amber-colored. 



Family GochUopodlda: — The .slug-like larv* of the Bombycoid family Cochliopodid:e, so 

 remarlcable from their snail-like mode of locomotion, their abdominal legs being entirely atro])hied, 

 in tlieir life history offer strong circumstantial evidence in favor of tlie primitive rapid accjuisitiou 

 of striking chai-acteristics at the lirst molt. These larvie, as we have elsewhere stated, are born 

 ■without traces of abdominal legs, are nearly colorless, and witli bodies more cylindrical than in the 

 full grown caterpillar. In the more .si)ecialized tuberculated and spiny genera Adoneta and Empre- 

 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 the gay varied colors and markings of 

 the body. This sudden change, after but a single molt, shows that these characters are suddenly 

 acquired. The larvai 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 exposed situation and of consequent successful adaptation to jirevent recognition on the 

 part of hostile insects and birds. The armature of poisonous glandular spines and the development 

 of b/right warning colors ai-e 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 familj*, I have 

 selected the following examples, copied from a previous paper:' 



KECAPITULATIO>' OF THE MORE SALIENT ONTOGENETIC FEATURES OF EMPRETIA STIMULEA. 



A. CONGENITAL FEATURES. 



1. The tubercles on the second and third thoracic and the first, seventh, and eighth abdominal 

 segments three times the size of those on abdominal segments 2-6, these tubercles being alreadj' 

 difl'erentiated 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 seta?. 



4. The body is more cylindrical than in the later stages and colorless. 



B. EVOLUTION OF ADAPTATKIXAI. FEATURES. 



1. In Stage II the form and general colors of the full-fed larva are assumed. 



2. The tubercles are now armed with numerous poisonous spinules. 



Note.— From wh.at 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. 



EECAPITULATION OF THE MORE SALIENT 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 Amer. Philosophical Society, Phil, xxxi, pp. 83-108, 1893. 



