306 Genus Ixodes 



pressure other than that of the coverglass, these papillae can still be 

 seen in their distended condition under a ^-inch objective" (see Fig. 

 283). 



Lewis (21. vi. 1901) quotes a letter from Wheler in which the latter 

 describes more fully his observations (previously referred to) made upon 

 ticks placed in a bottle and which entered into union in the manner 

 already described : " After about an hour I killed one pair with chloro- 

 form and examined the female, without result. A second pair separated 

 after a couple of hours. In this case plenty of spermatozoa were present 

 in the female. There seems no doubt that I had separated the first 

 pair prematurely. The third pair were still attached after 18 hours." 



Neumann (1906, p. 195) says correctly that coupling has actually 

 been observed in but few species of Ixodes, but that in view of the 

 homogeneity of the group it has been concluded that it is the rule in 

 Ixodoidea : " the sperm being removed from the genital pore by the </" 

 rostrum and introduced into the % pore." Neumann notes, as we have 

 done, that in no other genus of Ixodoidea are specimens received in 

 which the sexes have died united and remained coupled in the preserva- 

 tive fluid in which they were placed. He attributes this to the peculiar 

 sexual dimorphism affecting the hypostome in Ixodes, meaning doubtless 

 that the hypostomal teeth in the ^s are especially prominent. I 

 agree that this appears to be the cause of the prolonged union not 

 observed in any other genera and of many coupled pairs dying in situ. 

 I may note, however, that in /. putus </ the hypostome is practically 

 unarmed, but that nevertheless the sexes couple as do other Ixodes. 

 The subject certainly needs further study on living ticks (see further 

 on pp. 317, 334-345). 



We have received many specimens of ricinus in alcohol which have 

 died coupled, and frequently observed the coupled sexes alive on 

 different hosts. Unfed and partially fed or replete females in captivity 

 are promptly sought by the males. Under these conditions a male may 

 be repeatedly driven away from a female and it will repeatedly return. 

 At times the male is readily separated from the female ; at other times 

 it dies in situ. Bertkau's observation, cited above, that females 

 captured in a free state are rarely fertilized is doubtless explained by 

 what Wheler (1906, p. 426) states regarding his never having found 

 unfed females and males coupling under natural conditions upon herbage. 

 On the other hand, when the unfed sexes were placed in a bottle, which 

 was warmed by being carried in the pocket, coupling usually took, place 

 and lasted for hours. Samson (1909, p. 186) states that unfed Js may 



