84 



shall I succeed in filling the void. Meanwhile I cherish the hope that 

 in presenting these observations, however imperfect they may be, I 

 ofifer a not entirely valueless contribution to our knowledge of the 

 Ontogeny and Phylogeny of caterpillars. 



My researches have been guided by the ideas which Weismann has 

 presented in the above-named treatise, except that my object has been 

 less to represent the coloring and markings of the caterpillars, which, 

 indeed, are not always distinctly seen in alcoholic specimens. I have 

 given more prominence to the appendages of the skin, that is to say, 

 the form and distribution of the bristles, and the size and position of 

 the warts, which serve as a base for the brisdes. However insignificant 

 these for the most part microscopic objects may be, it will be seen that 

 many interesting inferences may be drawn from their changes in the 

 course of Ontogeny. 



I proceed to give, first of all, a description of the caterpillars as 

 named, in order that I may, in conclusion, arrive with greater certainty 

 at the general results. 



DESCRIPTION OF THE CATERPILLARS. 

 PAPILIONIDiE. 



I have before me nearly complete series of five species, viz. : Papilio 

 Astej'ias, P. Turnus, P. Troilus, P. Ajax, and P. Philenor, all from 

 North America, while of our own P. Machaon, I have received only 

 the first and second stages. Of P. Brevicanda, Mr. Edwards' work 

 (Butterflies of N. America) gives figures of all the preparatory stages, 

 which have been of use to illustrate certain points. 



Papilio Asterias. First Stage (fig. i). The general color of 

 the caterpillar at this stage is deep black, interrupted only by a white 

 spot, which lies like a saddle across the back of the third and fourth 

 abdominal segments. The caterpillar is thickly beset with hairs or 

 bristles which, for the most part, do not spring directly from the skin 

 but from warts or knobs. These are chiefly arranged in four rows, 

 namely, a sub-dorsal and a supra-stigmal row on each side. In addi- 

 tion to these, smaller infra-stigmal warts may be seen, and also similar 

 ones near the dorsal line, which bear only a single bristle. On the 

 head and on the last abdominal segment, as well as near the ventral 

 space of every segment bristles are also distributed in moderate num- 

 bers. 



Looking at the two principal rows of warts, namely the sub-dorsal 

 and the supra-stigmal, it will be seen that the largest warts are on the 

 thoracic and the last abdominal rings; indeed, the most prominent are 

 on the first thoracic and the last abdominal, and from these to the 

 middle the warts gradually become smaller. 



