BKITISH HYMENOPTEBA ANTHOPHILA. 411 



tongue of the Obtusilingues to the long filiform one of the higher 

 Apidce ; that the lora or /^-shaped hinge by which the meutum 

 and lingua can be projected is more developed in the higher 

 genera, and accordingly allows of greater play for those organs ; 

 that the basal joints of the labial palpi are flattened and sheath- 

 like in the higher genera, so as to form a protection for the base 

 of the tongue ; and that the paraglossse also tend, in these genera, 

 to take a sheath-like form. In the early genera the lora can 

 scarcely be said to exist definitely at all, the membrane between 

 the cardines being merely chitinized towards the apex and raised 

 so as to form an arch which acts as a hinge ; in Halictus, 

 Spliecodes, &c. even this is absent (see descriptions of those 

 genera). There appears to be a regular progression in develop- 

 ment, but this progression is arrested here and there by certain 

 genera which seem to defy one to find a proper place for them. 

 Such a genus is BopTiites. It has the labial palpi of the higher 

 Apidge, paraglossse quite unlike in form to those of any other 

 genus, no definite lora, in this respect resembling SpJiecodes and 

 Halictus, to which latter genus it greatly assimilates in general 

 appearance, and a tongue as long as that of any of the Apidje. 

 Panurgus, again, is quite aberrant and difficult to localize in any 

 arrangement, as, apart from its lingual peculiarities, its genital 

 armature is quite unlike that of any of the genera that could be 

 considered allied to it. These special features, however, will be 

 described more fully under each genus. 



The cibarial apparatus in all the genera is arranged on the 

 same general plan as in Apis, but varies very considerably in its 

 details, both as to the shape and the relative proportions of its 

 component parts, and it is on the characters afforded by some of 

 these variations that many of the diff"erent genera have been 

 established. I propose here to give a general description of the 

 apparatus, leaving the special features of each genus to be con- 

 sidered further on. 



At the back of the head, behind the face, between the occipital 

 foramen and the mandibles, is a deep wide groove, with abruptly 

 truncate sides, which lie nearly parallel to each other ; it is 

 determined somewhat semicircularly at its basal or occipital end, 

 i.e. that nearest the juncture of the head and thorax, but is open 

 at its apical end, except when closed by the mandibles folding 

 across it. The floor of the groove is the posterior surface of the 

 actual wall of the face. It is in this groove that the cibarial 



