26 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 63 



nently mounted. In these antennae there is no dark pigment to obscure 

 any of the antennal organs. To illustrate these various structures 

 modified copies of Schenk's drawings (1903) are given (fig. i). 



Figure i, A, shows the small bright spots (ForPl) on the drone 

 antenna magnified 150 times. This drawing also shows still smaller 

 bright spots (FFl) which are difficult to find. Formerly the larger 

 bright spots were termed " pits " but later they were called " pore 

 plates," " pore canals," and " sensilla placodea," while the smaller 

 spots bear the names " Forel's flasks " and " sensilla ampuUacea." 

 In this discussion the former will be known as pore plates and the 

 latter as Forel's flasks. Figure i, B, represents these organs of the 

 drone bee enlarged 600 diameters. Figure i, C, shows the pore plates 

 (PorPl) and two kinds of hairs from the antenna of a worker, en- 

 larged 600 diameters. The stouter of these hairs (Fg) bear the 

 names, " pegs," " clubs," and " sensilla basiconica," and the more 

 slender ones (THr) " hairlike structures " and " sensilla trichodea." 

 In this discussion the stout hairs are designated pegs and the 

 slender ones tactile hairs. A fifth antennal organ whose external 

 opening is not drawn by Schenk has the same superficial appear- 

 ance as Forel's flasks and probably cannot be distinguished from 

 them externally. These structures have been termed " pit pegs," 

 " champagne-cork organs," and " sensilla coeloconica." They are 

 here designated pit pegs. 



Figure i, D-H, show the internal anatomy of the five antennal 

 sense organs. Figure i, D, shows the structure of a pore plate and 

 of a tactile hair. The chitin (Ch) is solid black, the sense fibers (SF) 

 and sense cell ganglion (SCG) are represented by fine broken lines. 

 Since the sense fibers in Schenk's drawing are defective and are not 

 attached to the plate (PI) as the writer has observed them many 

 times in his sections, and as Schenk represents them in Vespa, they 

 are here drawn as they really exist. The plate is a hard and compara- 

 tively thick chitinous disc completely covering the pore canal (PorCl) . 

 However, at its margin there is a deep groove (Gv) entirely sur- 

 rounding the plate. To stimulate the sense fibers attached to the 

 plate the odors must first pass through this hard chitinous plate. 



Figure i, E, shows a peg with its sense fibers running half-way 

 to the tip of the hair. At its base the chitin is relatively thick while 

 at the tip it is thin. If this structure is an olfactory organ, the odors 

 must first pass through the thin chitin at the tip of the peg to stimulate 

 the sense fibers. Figure i, F, is a tactile hair. Figure i, G and H, 

 represent a Forel's flask and a pit peg respectively. Both of these 



