PARASITES 109 



out doubt, of the greatest possible interest. Their 

 systematic position has ever been a puzzle to 

 zoologists, and even now is a matter of contro- 

 versy. They have been looked upon as Hirudtnea 

 by Winsberg (1765), Cestoda by Chabert (1787), 

 Acanthocephala by Humboldt (1808), Trematoda by 

 Rudolphi (1809), and Nematoda by Nordmann (1832). 

 It was Van Beneden (1848) who first recognized 

 their Arthropod nature, but he placed them amongst 

 the Crustacea. Schubart (1853) suggested that their 

 proper position is amongst the Mites (Acarina), and 

 Leuckart (i860) adduced important anatomical and 

 embryological evidence in support of this view, 

 which was confirmed by Railliet in 1883 and by 

 Sambon in 1910. 



No less than three out of the four genera of 

 Linguatulids so far established are represented by 

 species parasitic on snakes. They are the genera 

 Porocephalus, Reighardia, and Raillietiella. 



The genus Porocephalus is of special interest, 

 because some of its species, such as Porocephalus 

 armillatus, a parasite of African Pythons (Python 

 regius, P. sebce) and Puff-adders (Bitis arietans, 

 B. nasicomis, B. gabonica), and Porocephalus monili- 

 formis, a parasite of Oriental Pythons {Python 

 molurus, P. reticulatus), are, in their nymphal stage, 

 deadly parasites of mammals, including man. 



The genus Reighardia was established by Professor 

 H. B. Ward, in 1899, for a Linguatulid of gulls and 



