206 AMERICAN HYMENOPTERA. 



obviously in a class by themselves, is our reason for calling them, as a 

 class, "compound spines." These spines have evidently been de- 

 veloped to perform special functions, and they will be discussed else- 

 where. 



The surfaces of movable chitinous plates, which are partially or 

 entirely lapped by other plates, are usually more or less striate or 

 reticulate on the covered portions. This is principally true of the plates 

 of the abdomen, including the spathae of the male genitalia (figs. 148, 

 152, 153, 155 and 174). Various parts of the legs are very finely reticu- 

 lated, and this reticulation is, on some parts, mixed in with the punc- 

 tures. 



Black, yellow, ferruginous and white make up the list of 

 general bumble-bee colors. Brown pile is sometimes very 

 noticeable with poor specimens and is, to a slight extent, 

 always present. This color does not appear to be normal, 

 as a rule, for the pile (dorsum of abdomen of handlirschi is 

 an exception to this and there are some others) and is, doubt- 

 less, usually the result of a failure in complete color develop- 

 ment on the part of normally black hair. It is, however, 

 perhaps the most common color seen in the wings, though 

 these organs are sometimes nearly hyaline. Very dark brown 

 wings usually have violaceous reflections also. 



Black is the most universal of the bumble-bee colors. The 

 visible portions of the integument of the main body seg- 

 ments, in undissected specimens, are, as a rule, almost en- 

 tirely of this color. 



Very few species {handlirschi) fail to have a noticeable 

 amount of black pile either on the main part of the body or 

 on the legs. As far as the clothing is concerned, this color 

 is most constant and universal on the legs, on the venter 

 and on the cheeks behind the eyes. It is also present on the 

 two apical dorsal abdominal segments, on the dorsum of the 

 thorax between the bases of tbe wings, and on the frons on 

 a very large percentage of the New World species. It is 

 probably least often present in any amount on the anterior 

 portion of the thoracic dorsum. 



Next to black, yellow is the leading color. While present 

 to a greater or less extent on most species, it is entirely 

 absent with some (e. g. — dahlbomii, funebris, handlirschi, 

 rubicundus, volucelloides) . It is probably most constantly 



