48 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 65 



cervical plate, as already described by the present writer, because 

 either in sections or in whole mounts of the integuments of the heads 

 it is often difficult to determine whether the pores lie on the pharyn- 

 geal plate or on the cervical plate. Janet (1911) saw the same 

 organs widely distributed over the integument of the mandibles of the 

 honey bee. According to him, all the pores, whether on the mouth- 

 parts or on the legs, have a similar structure, and they resemble the 

 structure of the olfactory pores described by the present writer ; how- 

 ever, there are a few slight differences. He calls the chitinous cone an 

 umbel, which is always separated from the surrounding chitin by a 

 chamber. This chamber communicates with the exterior by means of 

 the pore. The sense fiber, or his manubrium, runs into the umbel, 

 and he thinks that it spreads out over the inner surface of the umbel 

 and does not open into the chamber. Thus the umbel forms a thin 

 layer of chitin which separates the end of the sense fiber from the 

 external air. Janet thinks that the role of these organs is evidently 

 to permit the end of the nerve to become distributed on a surface 

 relatively large and separated from the air only by a thin layer of 

 permeable chitin. He imagines that they are special olfactory organs, 

 but different from the olfactory organs on the antennse. In regard to 

 those on the mandibles, he believes that they aid in building comb and 

 in collecting pollen and propolis. 



Hochreuther (1912) found a few olfactory pores on the epicranium 

 near the margin of the eyes, 11 on the first and second joints of the 

 antennas, a few on the dorsal side of the labrum, very few on the 

 dorsal side of the mandibles, several on the maxillae and many on the 

 legs of Dytiscus marginalis. He called them dome-shaped organs 

 and describes and gives drawings of them in a manner somewhat 

 similar to that of Janet. 



We shall now discuss the innervated hairs only briefly, because, as 

 already pointed out, they probably serve neither as olfactory organs 

 nor as gustatory organs. 



Wolff (1875) was the first to describe the hairs on the epipharynx. 

 In the honey bee he described each organ as a small cone with a pit 

 in the summit bearing a small hair. He thought that each hair is con- 

 nected with a sense cell group and that these organs receive olfactory 

 stimuli. 



Kunkel and Gazagnaire (1881) found innervated hairs on the 

 paraglossse, on the epipharynx and on the pharyngeal plate of Diptera. 

 They imagined that these hairs receive gustatory stimuli. 



