NORTH AMERICAN DIPTERA. 



331 



The galea is distinctly divided at the tip, forming evident lobes, 

 covered with a delicate membrane, which is wrinkled, but is not 

 furnished with pseudo-trachea. 



Because nearly allied to Bomhylius we may now examine Anthrax, 

 although not nearest in any direct line of development save for the 

 palpifer. As in Bombylius, the j)roboscis is so fixedly projected for- 

 ward, that it is difficult to straighten, and the mouth parts are there- 

 fore figured lying against the fulcrum. Here, too, a study of the 

 method of union of labium to fulcrum, points to the mentum or 

 submentum, as concerned in the development of that organ. The 

 lacinia have become broad, roughly shaped like a spear-head ; they 

 envelope the labium, and, with it, lie in the galea. The subgalea is 



distinctly paired, each side 

 piece divided longitudinally, 

 so that here we see the begin- 

 ning of the central supporting 

 rods, well developed in Eris- 

 talis, and also the foundation 

 of the structure forming the 

 broad back plate of the oper- 

 culum or medi-proboscis. The 

 labellate development of the 

 galea is well marked, though 

 the lobes are not well divided. The chitinous parts of the two joints 

 are reduced to two pairs of small plates, which alone indicate the 

 original nature of the structure. The most interesting character is in 

 the palpifer. Heretofore we have seen the palpus attached at or near 

 base, and always in forms in which the proboscis is not flexed. In 

 BomhyUns we saw the first approach to a basal prolongation, which in 

 Anthrax is much more marked. The palpus is small and feeble ; the 

 basal prolongation of the palpifer is not long, but it is broad, flattened, 

 roughened as for muscular attachment, and very thoroughly chitin- 

 ized. The apical process is very decidedly less chitinized, and does 

 not extend to the tip of the labium. As is lisual, its point of inser- 

 tion is outside of the galea, which it enters with its apical process, 

 very close to base. 



Beginning a new series, not so closely connected with those forms 

 in which the mouth parts are adapted for piercing, are a number of 

 species in which the galea is well developed into the labellate form 

 still, however, retaining the marks of its origin in a remarkably 

 perfect condition, and having the proboscis not hinged. 



Fig. 12. Mouth parts of Anthrax 



