364 PROCEEDINGS OF THE AMERICAN ACADEMY. 



Take, for example, the larval Nadata gibbosa ; this, like the cater- 

 pillar of Gluphisia and of Lophodonta is a smooth-bodied larva, 

 ornamented with lines, but entirely unarmed. The life history tf 

 N. gibbosa shows that it is born with a smooth body, without any 

 rudiments of tubercles or enlarged bristles, while no traces of the 

 yellowish subdorsal lines appear until at the end of the second stage. 

 This form is therefore a primitive one, and this fact would seem to 

 demonstrate that the humps, tubercles, and spines, so frequently ob- 

 served in the group, arose within recent geological times, and were 

 acquired during the postembryonic stages of the larvae of different 

 genera, in response to various changes in the surroundings of different 

 species, these finally becoming fixed and regularly transmitted along 

 various lines of development, definite when the changes in the envi- 

 ronment are definite, and resulting in a series of forms constituting the 

 present genera of the family. 



One of the most notable cases in the family is that of the loss at 

 about the middle of the larval life of the remarkable antlers of Hete- 

 rocampa biitndata. During the three earliest stages the larva bears 

 on the prothoracic segment a pair of enormous autlers, each with 

 four tines. At the second moult these are discarded, and in the last 

 two stages are represented by a pair of conical, rounded, polished, 

 piliferous knobs. The rest of the partly grown body of the larva is 

 smooth. After casting its horns the larva assumes a new ?et of color- 

 ational markings, so that in its last two stages it is a total lv different 

 creature in appearance from the earlier stages. 



I have also observed the wonderful changes undergone by the 

 caterpillar of Heterocampa guttivvtta, representing five stages, nearly 

 every one of which presents notable differences. In the first, directly 

 after hatching, the reddish larva has not only a pair of enormous 

 antlers with four tines on the first thoracic segment, but a pair 

 of long antler-like spines on abdominal segments 1 to 6. and also 

 8 and 9 ; those on segments 1 and 8 being about three times as large 

 as the others. It is certainly one of the most singular larvae of 

 the family. 



Now this bizarre armature is entirely discarded at the first moult, 

 excepting' that the prothoracic antlers are represented by a pair of 

 knob-like tubercles, the other segments, however, showing no trace of 

 the former existence of spines. Also, while the body was not striped 

 in Stage I., it is now paler red with a more brownish tint, and is marked 

 with four yellowish stripes. At the end of this stage the lines become 

 effaced, and the body grows more yellowish on the sides. In the third 



