32 BRITISH BEES. 



extending forwards, hence takes several forms, usually 

 tapering to an acute point, but sometimes rounded or 

 hastate, according to the structure of the tongue, to 

 which they form a protection. 



The maxillary palpi are small, longitudinal joints, 

 never exceeding six in number, and generally in the 

 normal or true bees not so numerous. They vary in 

 relative length to the organ to which they are attached, 

 and usually progressively decrease in length and size 

 from the basal ones to the apical, but each joint, except- 

 ing the terminal one, is generally more robust at its 

 apex than at its own special base. The function of these 

 maxillary palpi is unknown. They are always present 

 in full number in the Andrenidce, and in some few 

 genera of the true bees, but they vary from their normal 

 number of six to five, four, three, two, and one in the 

 latter ; and it is curious that they are most deficient in 

 those bees having the most complicated economy, as in 

 the artisan bees and the cenobite bees ; they thus evi- 

 dently show that it is not a very paramount function 

 that they perform. On each side, at the apical summit 

 of the labium, are inserted the labial palpi. These are 

 invariably four in number, but vary considerably in 

 length and substance. In the Andrenidte they have 

 always the form of subclavate, robust joints, and are 

 usually as long as the tongue, but not always ; they are 

 only half the length of that organ in the subsection of 

 the acute-tongued Andrenidae. In the normal bees, 

 even in the genus Panurgus, which is the most closely 

 allied to the Andrenidae, the labial palpi immediately 

 take excessive development, especially in their two basal 

 joints, and the structure of these two joints, excepting 

 in this genus and in Nomada, partakes of a flattened form 



