386 William Morton Wheeler 



or ova degenerate in their follicles and are evidently quite incap- 

 able of development, in the male there may be ripe spermatozoa 

 in at least one of the testes. Perkins found motile spermatozoa in 

 all the stylopized males which he dissected, and Perez mentions a 

 male of Andrena decipiens taken in copula, so that this sex mav 

 retam, at least occasionall)/, not only the normal mating instincts, 

 but the ability to fecundate normal females. The parasites before 

 maturity live on the fat-body and blood-tissue of their hosts and 

 do not attack the other organs directly. These undergo partial 

 atrophy through lack of nutrition. Observations similar to those 

 of Perez have been published by Saunders ('82) and Schmiede- 

 knecht ('83).3 



Turning now to Polistes, we find that in this genus the secondary 

 sexual characters are in certain respects quite as clearly developed 

 as in the andrenine bees, but as wasps do not collect pollen, the 

 hind legs show no special modifications in the female. The fol- 

 lowing are the main external sexual differences observable in 

 PoHstes metricus: The male has a slender thorax and long, nar- 

 row abdomen. The antennae are 13-jointed, with a long, slender 

 funiculus, not enlarging towards its tip; the second funicular 

 joint is little if any longer than the two succeeding joints taken 

 together. The face is long and narrow, with a pair of longitudinal 

 grooves running from the antennal insertions to the clypeus and 

 separated by a prominent longitudinal welt or elevation. The 

 clypeus is flat or even slightly concave and its surface is impunc- 

 tate. The whole face and clypeus, the anterior surface of the anten- 

 nae to within a few joints of the tip of the funiculus, the anterior 

 surface of the coxae, femora and tibiae, a series of transverse 

 bands or spots on the abdominal sternites behind as well as in- 

 cluding the first segment, are sulphur yellow. The two large ferru- 

 ginous spots on the first abdominal segment are usually well- 

 developed. 



In the female the thorax is proportionally stouter and the 



'Though the publications of these authors antedate the article above reviewed, we are not to infer 

 that this implies priority of discovery. Perez says that he originally called the attention of these in- 

 vestigators to the facts and had himself published a preliminary account of his researches as early as 

 1880 in the Revue Internationale des Sciences. Tome I. 



