MEGACHILE. 271 



The MALES of the first division differ in having ths 

 head slightly larger and squarer above; the antennae 

 very slightly longer; the mandibles more acutely tri- 

 dentate, with a distinct powerful basal tooth beneath, 

 terminating the concavity of the organ ; the anterior 

 femora, tibia, and joints of their tarsi, excepting the ter- 

 minal one, concavo-convex, the four first joints of the 

 latter distended laterally, and edged with a dense fringe of 

 setse, the distension of these joints is widest at their arti- 

 culation with the tibise and they decline in length to the 

 claw joint which is long; the claws bifid; the interior 

 claw acute, but remote from the apical one ; the posterior 

 femora are very robust, their tibiae much curved, robust, 

 almost triangular, and externally very convex; their 

 plants almost glabrous, not so long as the three follow- 

 ing joints, externally rather twisted, and beneath fur- 

 nished with a dense brush of long stiff hair. 



In the second division of the genus the males are des- 

 titute of the distension of the anterior t#rsi, these being 

 instead densely fimbriated externally ; the legs in them 

 are much less robust, and more closely resemble those of 

 their females. 



NATIVE SPECIES. 



Anterior tarsi of males mucli dilated. 



1. Willuyhbiella, Kirby, $ ? . 5-7 lines. 



2. maritima, Kirby, $ ? . 6-7 lines. (Plate XII. 



fig.2<? ?.) 



3. circumcincta, Kirby, $ ? . 4^-5 \ lines. 



Anterior tarsi of males not dilated. 



1. ligniseca, Kirby, $ ? . 5-7 lines. 



2. centuncularis, Linnseus, <J ? . 4-6 lines. 

 centuncularis, Kirby. 



