32 SILKWORMS. 



in which it works ; it is succeeded by a minute joint, the trochanter, 

 which cannot be seen till the leg is bared of scales, when it appears 

 as a triangular piece attached obliquely to the end of the coxa ; 

 next comes a much larger and rather stout cylindrical piece set 

 on at an angle to the coxa, and loosely furnished with long hairs ; 

 this is \\~\efemnr, or thigh ; this is succeeded by a curved thinner 

 piece, the tibia, or shank, carrying a dense brush of hairs at the 

 side and two movable spurs at the further end; lastly comes the 

 tarsus, or foot, which is itself composed of five joints, of which 

 the first is by far the longest. The last joint of the tarsus carries 

 a pair of curved claws, by which the moth can cling to any sup- 

 port that exhibits the slightest roughness of surface. All the 

 tarsal joints are covered above with creamy scales, which give 

 them a curious appearance, reminding one of the feathers down 

 the legs and toes of Cochin China fowls. Between the two claws 

 is a minute pad. When the moth walks it supports itself on its 

 flexible tarsus, clinging with its claws to any irregularity of the 

 surface, and placing its shank and thigh at an angle to one 

 another. 



The wings are really composed of a delicate transparent skin or 

 membrane, strengthened and kept in position by a number of fine 

 tubes, called nervures, branching out from the point of attachment 

 to the thorax ; it is in these tubes that the fluid referred to above 

 at first courses for the extension of the wings, but in the fully 

 formed moth they are dry and stiff. The nervures do not, as 

 might be supposed, branch about the wings in an indiscriminate 

 way ; they always follow a definite course, and are constant in 

 number, so that it has been found possible to assign names to 

 them individually, and to the areas into which by their branchings 

 they divide the wings. The arrangement of the nervures, or the 

 neuration, as it is called, varies a good deal in different groups 

 of moths, and is therefore largely employed as an aid to classifica- 

 tion. The name " nervure " is rather an unfortunate one for these 

 minute tubes, suggesting as it does some affinity with nerves, with 

 which, however, they have nothing whatever to do. 



The clear, membranous wing is completely covered, above and 

 below, with a vast number of exceedingly minute scales, of very 

 varied shapes, but so small, that to the naked eye they appear 

 simply as so much fine dust. If the wings be roughly handled, 

 they readily come off on the fingers. It is these scales that pro- 

 duce the pattern on the wings, which, without them, would have 

 no more adornment than a clear piece of window glass. Each 

 scale is a flat body, terminating at one end in a single point, and 

 at the other in a number of pointed projections, of different 



