48 INTRODUCTION. 



The abdomen is long, slender, and compressed, in the section which connects this 

 and the second stirps ; it is somewhat shorter in the typical species, and more robust 

 and suddenly attenuated near the confines of the fourth stirps. The proboscis is 

 generally long and robust. 



Thvsanuriform Stirps. The characteristic mark of the larva of this stirps is an 

 appendage to the posterior part of the body, consisting of two rigid setae or spines, 

 pointing directly backward. These setae vary, indeed, in length and size, but their 

 existence, in the individuals of the stirps, is general and without exception. This appen- 

 dage has also been denominated a bifid tail or a furcula, from its forked appearance 

 in many cases ; it is more developed in some subjects than in others ; it likewise 

 varies in its consistence, colour, and mode of attachment. In some cases these 

 spines or setae are an immediate continuation of the substance of the larva, in others 

 they difier in colour and texture, and the union to the body is by an articula- 

 tion. This larva is peculiarly abundant in temperate regions ; it unites, in the 

 European Fauna, more species in one group than any other form of larva. This will 

 appear by reference to the Wiener Verzeichnis, where the family named from the 

 larva Subfurcata, consists of twenty-three species, most of which are known in aU 

 stages of their metamorphosis. Nearly one hundi'ed European species are de- 

 scribed in systematic works. The Javanese series consists of a smaller number, 

 and among this there are several which deviate considerably from the regular 

 typical form. In the latter the larva is cylindrical, long, attenuated in a greater or 

 less degree at both ends, but upon the whole, thicker anteriorly : the form of the 

 head is greatly diversified, it is either simple and rounded, or depressed anteriorly 

 with two lateral erect setaj or horns. In some cases the head is greatly distended 

 posteriorly, in form of a shield, which is moveable and crowned with four or more 

 horns, having serrate edges. Several of the larvae of this stirps have a tuft of hair 

 on the head and two transverse hairy ridges on the neck, in consequence of which 

 they have an analogical resemblance to the larvae of one of the stirpes of the Bom- 

 bycidae. Among the foreign individuals of this group, various very grotesque forms 

 are observed, and the lateral appendages are sometimes greatly developed. 



The peculiarities of the larva of this stirps, and more especially the two setee or 

 caudal appendages, strongly remind us of the Thysanura, and the character of the 

 perfect insect confirms this analogy ; we find in the Lepidoptera which belong to it, 

 the long setiform antennas, which are mentioned by Mr. Macleay, Hor. Ent., p. 351, 

 as a peculiar properly of the Lepismce ; their form is also, on the whole, more 

 elongate than that of the larvse of the other stirpes. 



The pupa of this stirps is smooth, shining, often handsomely variegated with 

 colours, but never -gilt : its form is subject to many modifications, being regularly 



oval. 



