INTRODUCTION. 59 



appendage on each shoulder, having the appearance 

 of a lappet ; these are named tegulce or base- covers, 

 and are well exemplified in the genus Lithosia and 

 its affinities. This part of the hody often bears one 

 or more conspicuous dorsal tufts of feathery hair- 

 like scales, of which the anterior and posterior are 

 sometimes concave ; in which case the former has 

 the concavity directed forwards, and the latter has 

 it turned in an opposite direction. 



As appendages of the thorax, the legs next require 

 a brief notice, but they present nothing very peculiar 

 in their formation. An exception to this character, 

 however, is perhaps to be found in the occasional 

 great length of the coxae, which in the anterior legs 

 of certain species (Hypena proboscidalis, for ex- 

 ample) are as long as the tibiae, and not much 

 shorter than the thighs. The two last named 

 divisions of the leg are often densely clothed with 

 long hairs, and the tibiae, in the fore pair, are usually 

 furnished with a strong spine on the inner side, 

 which sometimes assumes the appearance of a rigid 

 compressed lobe. In most cases this is the only 

 projection on the anterior legs ; the intermediate 

 tibiae generally have two spurs at the apex, and 

 besides a similar pair in the hinder ones, there are 

 often two others in the middle. The latter arrange- 

 ment is frequently observed also in the intermediate 

 tibiae. This portion of the leg often bears a pen- 

 dant tuft of loose hair, which probably assists in 

 balancing the body during flight 5 and in some in- 

 stances (as in the genus Alcis) the tibiae have a 



