( cxc ) 



sometimes distinguish a 5 as belonging to a particular genus 

 or species (e. g. Coelioxys) ; but when it differs conspicuously 

 from that of the $, it is generally because it is simpler 

 (nearer the " type " of its group), so that it is really the ^ 

 which shows the Sexual character. 



Probably the clearest and most important case of a true 

 sexual $ character in the abdomen is the development in 

 certain Bees {Osmia, Megachile, Anthidium, etc. = the sub- 

 family of the "■ Gastrilegidae") of extreme pilosity on its 

 ventral surface^ which answers the same purpose as the 

 pilosity of the hind-legs in other Bee-genera — viz. to form 

 a brush for accumulating pollen. But even this is only an 

 augmentation of the specific pilosity inherited by both sexes. 



I know no case of paradoxical teeth, spines, etc., such 

 as often occur in $ ^, on the dorsal apex of any $ 

 Aculeate ; and only one (which I have read of but not seen) 

 of such charactei's being conspicuously developed on the 

 ventral surface of a $ abdomen. This is the case of a Fossor 

 {Stizus gynandromorphus, Handlirsch) ; and as only a single 

 specimen seems to have occurred, and its ^ is unknown, 

 one is tempted to suspect it may be a monstrosity. 



The difference as to the number of visible segments in the 

 (J and the $ abdomen has been mentioned already ; and if 

 this difference, and the simpler structure of the dorsal and 

 ventral apical segments of the $, be excluded, I do not know 

 that any important Secondary Sexual character occurs in the 

 abdomen of any $ Aculeate, except the ventral pollen-brush 

 of the Gastrilegidae, and possibly the spine-like last ventral 

 segment of Coelioxys ?, which pex^haps facilitates its para- 

 sitical ovipositions. 



(5) Apteroics Aculeates occur only among the Ants (whose 

 workers are always in this condition), and in one group of 

 Fossors (the Mutillidae). All European and Mediterranean 

 Mutillidae have wingless 9 $ ; and I have already given 

 reasons for thinking that this character, as is usually the case 

 with ? characters, is an advantage to the ? ?, in fulfilling 

 their duties as mothers-in-prospect. Very rarely $ S ^^ ^^is 

 group (in certain spp.) exhibit the same character, and I 

 suppose that, in such cases, the character has probably been 



