74 SAMUEL H. SCUDDER. 



the different groups diverged from each other or from the main stem ; 

 and the height which each branch attains, the relative perfection of 

 the highest members of that group. It is of course impossible to re- 

 present this with any accuracy on a flat surface; for one may properly 

 conceive of a group only as a mass, composed of branches springing 

 from a central core. The Equites and Ephori are thus brought at 

 opposite extremities of the tree, whereas they are closely related to 

 each other and disagree with all other groups, in the retractility of 

 the head of the caterpillar;* this relationship however is indicated by 

 each occupying the lowest twig of the branch on which it is seated, 

 and both branches being closely connected at their base. The striking 

 and unique peculiarities of certain groups is shown by their extreme 

 divergence from the main stem : thus the Equites or Swallow-tails 

 stand apart from all others in the possession of dorsal osmateria in the 

 caterpillar and in certain special characters of the butterfly, shortly 

 to be mentioned ; the Ephori or Lycasnids at the opposite extreme, in 

 the onisciform nature and diminutive heads of their caterpillars ; the 

 Castnioides among the skippers by their close approach to the moths jf 

 and the Satyrs (Oreades), by the forked tail of their caterpillars; the 

 superficial afiinity of this last group to the skippers is also indicated 

 on the diagram by the directness of their line from the very base. 

 It is one of the most curious features in the structure of butterflies 

 that its highest and lowest members should resemble each other in so 

 many minor points. For instance, the tone of coloring and pattern 

 of markings on the wings of many Satyrs, as well as the position and 

 general nature of the sexual marks on the front pair of some males, 

 find a close counterpart on the wings of some skippei-s ; so also the 

 chrysalids of Satyrs are among the simplest, most rounded and compact 

 in the whole family, approaching in this respect the lowest butterflies; 

 nevertheless in all the prime features of their organization, the Satyrs 

 outrank all others or divide the honoi-s with the Danaids. 



The Libytheans or snout butterflies are placed at no great distance 



*I do not know that attention has ever been drawn to this feature in the 

 caterpillars of Equites, since the time of Denis and Schiffermuller, who say 

 (Syst. Verz. Schmett. Wien, 161,-1775), " Diese Raupen . . . ziehen den kleinen 

 stumpfen Kopf gern unter den ersten Ring zuriick." When at rest the head 

 is nearly half concealed by the extended epidermis of the first body-segment, 

 and can be compared with nothing in other butterfly caterpillars, excepting 

 the complete retractility of the head in Lycsenids. 



I Cf. Riley's admirable paper entitled Notes on the Yucca Borer (Trans. Acad. 

 Sc. St. Louis, III, 323 seq.)j see also his Reports on the Insects of Missouri, 

 VIII, 169 seq., IX, 129. 



