124 STUDY OF 



as possible to the thorax by one movement, 

 raising their backs in a loop or bridge-Hke form : 

 they then hold fast by these spurious feet, whilst 

 they advance their fore parts with a similar move- 

 ment ; and, adhering securely by these claws to 

 the leaf or branch, they are enabled to elevate 

 and project their heads in almost any direction ; 

 the horse-shoe form, in which the claws are 

 arranged on the anal feet, giving them the 

 power of pressing forward with greater rapidity. 



In these examinations of larvae, I apprehend 

 we shall almost always find that the number and 

 arming of the prolegs or spurious feet, afford 

 regular specific indications, and that they are 

 seldom accidental varieties of any one species; 

 and, therefore, that it is, generally speaking, 

 unsafe to say, that the larvae of any species of 

 insect have from one number to another number 

 of prolegs or spurious feet ; and, considering that 

 the spurious feet are almost invariably fur- 

 nished with more or less of these horny claws, 

 the term membranaceous, which has been usually 

 given to them in contradistinction to the six 

 proper or horny feet, is a little incorrect. 



In counting the spurious feet of hundreds of 

 larvae of the tenthredo, which we are about to 

 consider, I do not remember ever finding an ex- 



