1910] A Structural Study of Some Caterpillars loi 



Thyatiridae , Drepanidae and Notodontidae the last legs either 

 disappear or are modified, while in the lowest Tineids they may 

 have never developed (Adela, Incurvaria). In the Encleidae 

 and Nepticula, as well as some other leaf -miners there are no 

 hooks at all on the prolegs, but the area of roughened skin in 

 Nepticula suggests an even more primitive condition than occurs 

 in Adela. 



The Lycaenidae, as well shown in Scudder's figure, have 

 developed an outer fleshy lobe, apparentl}^ from the planta. The 

 planta is apt to be unrecognizable in those which have lost the 

 outer part of the circle of hooks, but its retractor muscle serves 

 as in the lower ones to withdraw the hooks that remain. (Com- 

 pare Jasoniades with Papilio). 



In Lagoa the line of hooks is sharply angulate at the middle 

 and there the hooks are shortened. 



Another variation is in the arrangement of the hooks in the 

 band. In the most primitive forms all those in a single line are of 

 equal length gradually decreasing to the end, but a little higher 

 in the scale, there develops an alternation of length by which the 

 hooked tips are thrown into two or more ranks. In many of the 

 highest families the single length again prevails, apparently as a 

 secondary modification. In the lower forms (Micros) these two 

 arrangements intergrade, but in the Macros they separate 

 families or even superfamilies very sharply. 



The proleg typically bears four setae, three on the outer side 

 (vii) and one on the inner or anterior side (viii). The minute 

 primary ix may migrate up on to the anterior side. 



HOMOLOGIES AND NAMES OF THE PARTS OF THE HEAD. 



About the identity of the front and clypeus; and of course of 

 the mandibles, labrum, maxillae and labium as a whole, there 

 can be little or no doubt. The epicrania, as the name is used in 

 this paper, include also a number of other sclerites which are 

 fused with it so completely as to show no suture. A large part 

 of the epicrania becomes the compound eyes in the imago. The 

 postgenae will not be discussed to any extent, but they are quite 

 distinct. 



The naming of the parts of the maxillae and labium on the 

 other hand has been done mainly in order to refer to them intelli- 

 gibly. Such grounds as I have for this tentative homologizing 

 may be largely drawn from the figure of the Elaterid beetle larva, 



