ON THE TERMINOLOGY OF DIPTERA. XX111 



rally five-jointed ; the first joint is called metatarsus. At the tip 

 of the last joint there are two claws (ungues), and under each of 

 them there is generally a membranaceous appendage called pul- 

 vilhis. Besides these appendages, many families have between 

 them a third single appendage of similar structure, which is called 

 empodium; in other families this organ is bristle-like, or altogether 

 wanting. 



I have little to say about the expressions for the different cha- 

 racters of the surface and the clothing of the parts of the body of 

 Diptera ; I will observe only that the gradations hoary (pruinosus), 

 dusted (pollinosus), mealy (farinosus), or pubescent (pubescens), 

 hairy (pilosus), bristly (setosus), etc., in their application must be 

 judged more according to a relative than an absolute scale, viz., in 

 a family that has coarse hair the same is called hairy, which in 

 another with fine hair is termed bristly, and so in similar cases. 

 If we were not willing to do so, expressions would fail to point 

 out the existing differences. 



