Biology of I. ricimis 



309 



the vagina is everted and protruded forward and the egg issuing there- 

 from is received by a delicate bilobed, bladder-like organ which is pro- 

 truded over the depressed capitulum from beneath the scutum. Each 

 heart-shaped lobe possesses a finger-like protrusion anteriorly on the 

 inner side. This organ, to which Nuttall (1908, p. 398) gave the name 

 of Genu's organ, in honour of its discoverer, completely envelops the egg 

 as it emerges from the everted vagina. According to Gene - it takes 





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Fig. 284. 



Fig. 285. 



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Fig. 286. 



Figs. 284-287. Oviposition in Ixodes ricinus (Wheler, 1899, Fig. 20 ; also 1906, PI. V, 

 Fig. 3). We reproduce these figures from the author's original blocks as they very well 

 illustrate the successive stages of the process. In Fig. 284 the capitulum (" head ") is bent 

 downward to meet the advancing ovipositor. In Fig. 285 the palps are separated ; the 

 hypostome is hidden behind the ovipositor which has advanced still further and is pro- 

 truding an egg ; Genu's organ (" membrane") is protruded to receive the egg as it emerges 

 from the ovipositor. Fig. 286 shows Gene's organ enveloping the egg between its lobes. 

 In Fig. 287 the ovipositor is being withdrawn and the hypostome appears ; Gene's organ 

 is collapsing and carrying along the egg toward the basis capituli. These are the only 

 figures hitherto published adequately illustrating the process of oviposition in ricinus. 



