322 



JOHN B. SMITH. 



Fig. 2. Mouth parts of Polistes ^netricus. 



the galea, the palpifer and palpus, all of which are shown in the 



figure. 



The galea is often palpiform, and in that case the lacinia becomes 



developed into a scra- 

 ping or brushing organ, 

 sometimes adding a di- 

 gitus, but perhaps more 

 usually, the galea is the 

 most developed organ, 

 and is fjrmed as the 

 brush, while the lacinia 

 is reduced as in Polistes, 

 or, still more obviously, 

 in Macrodadylus, where 

 it becoQies a mere rudi- 

 ment, while the galea 

 becomes highly devel- 

 oped. To this development of the galea, the facts that it is two 



jointed, and that it tends to form processes or specialized hairs and 



bristles, particular attention is drawn. 



The labium in its simple form, consists of a central ligula, which 



is rarely paired, lateral para- 



glossse, and the labial palpi, 



all of which are attached to 



the mentum. Neither ligula 



nor paraglossse are usually 



jointed, except perhaps, in 



the Orthoptera. Often they 



are united to form a single 



organ, the ligula, practically 



imbedded in the united para- 



glossse. In the Ajndce, or 



many of them, the ligula be- 

 comes elongated, ringed, but 



not jointed, the paraglossse 



become enveloping membranes 



for a portion of the distance, 



and the palpi also become 



elongated as the figure of Andrena shows. To the peculiar labial 



development in Macrodadylus, attention is here called, but this will 



Fig. 3. Mouth parts of Macrodadylus siihspinosus 



