NEW MALLOl'HAOA. 



177 



represents more exactly the Amljlyceran structure, bat 

 tlie Isclmoceran may Ite 

 produced from ii by suj»- 

 [>ressin^ oue testis on each 

 side and drawing the other 

 two toward each otlier 

 wliile their distal ends are 

 turned in opposite direc- 

 tions. Nusbauui states 

 that in Lipeurus baciUus 

 and in (roniocotefi hologas- 

 ter, two Isclmoceran spec- 

 ies, the fundaments of the 

 testes in the embryos form 

 each tliree k)bes, of wliich 

 the posterior two develop 

 into testes, while tlie anter- 

 ior one atroj)hies. This 

 anterior lobe, if it repre- 

 sents a third testis, establishes three on each side as the 

 typical number of testes in the whole order. 



In Physontomum dijfusinn (plate xiii, lig. 9) tlie testes 

 are rather small. The most anterior is situated rela- 

 tively rather far in front of the others, and is trian- 

 gular in outline, having the base turned forward. Its 

 posterior end becomes rather gradually narrowed, pass- 

 ing into the vas deferens. The middle and jjosterior 

 testes are enlarged toward their bases and i)t)inted at 

 their distal ends. Each is connected with the vas 

 deferens by a short vas efferens. The sperm duct runs 

 a short distance back of the last testis and then turns 

 forward to the seminal vesicle. This organ lies in the 

 third abdominal segment. It is rather small, being 

 about the length of the segment in which it is situated. 



Fig. 4. — Diagram of tlie intemul rppro- 

 (liu-tive organo of the male Mallophaga; t. 

 tfstes: rd, vasa deferentia: m', vesicula 

 seminalis. 



