82 



REPORT 108, U. S. DEPARTMENT OF AGRICULTURE. 



country; similar species, with the dorsal shield broken up into numerous small ones, 

 are found in northern Europe. 



The genus Raillietia Trouessart is based on the Gamamis auris Leidy, taken from 

 the ears of cattle. It is closely related to Parasitus, the male having the second pair 



Fig. 156.— Caelenopsis americana. (Author's illustra- 

 tion.) 



Fig. 157. — Sejus americanus. (Author's 

 illustration.) 



of legs calcarate. Trouessart thought he had observed parthenogenesis in this species 

 but he was probably in error, as various cases of supposed parthenogenesis have been 

 shown to have been mistakes. 



Fig. 158.— Paro- 

 grecniaalfkcni- 

 (Original.) 



Fig. 159. — Laclap!^ ccliidvivus. (Original.) 



lldirozcrcon is based on a 8outli American species (only the female known) in 

 which there is a suckerlike disk each side of the anus; the dorsal shield is entire, 

 the })eritreme long, and leg 1 with claws. Discozcrcon, from Java, is a similar form. 



