GAMASID^ 



693 



Family i : Dermanyssid^. 



Gamasoidea parasitic on vertebrates, with mandibles fitted for piercing, 

 with the body sometimes constricted, with soft integuments finely striated. 



The Dermanyssidse are divided into two subfamilies : — Dermanyssinae, with 

 an anal plate; Halarachninae, without an anal plate. 



Subfamily Dermanyssinae. 

 Dermanyssus Duges, 1834. 

 Dermanyssinae with a long body not distinctly constricted; peritreme on 

 the venter, with chelate mandibles in the male and long stiliform mandibles 

 in the female. Parasitic on birds. 



Dermanyssus gallinse Redi, 1674. 



Synonyms. — Pulex gallince Redi, 1674; Acarus gallincB de Geer, 1778; Der- 

 manyssus avium Dugds, 1836. 



This parasite lives in cracks, etc., in the hen-house during the day, and 

 attacks the fowls at night, sucking the blood. It is also found on many other 

 birds and mammals, and occasionally on man, generally on poultry-men, in 

 whom it produces a papular eczematous dermatitis on the back of the hands 

 and forearms. D. hirudinis Hermann, 1804, which is probably only a variety 

 of this species, can also be found on man. 



Morphology. — Body egg-shaped, posterior end wider than anterior, abdo- 

 men with short, marginal, widely separated bristles. 



Male, 0'6 millimetre by 0*32 millimetre; female, 0*7 millimetre by 0-4 milli- 

 metre. ~ 

 HolothyrusGervais, 1842. 



Holothyrus coccinella Gervais, 1842. 

 This arachnid is found on ducks and geese in Mauritius, and is said to attack 

 human beings, causing swelling of the affected part, which, if the lips or tongue 

 of a child, may be dangerous. Some authorities consider that this arachnid 

 should form a separate family of its own — Holothyryidae. 



Family 2 : Gamasid^e. 



Ii;! this family comes the genus LcBlaps Koch, 1842, with its species L. echid- 

 ninus Berlese, mentioned in the chapter on Protozoa, because Miller has 

 traced the life-cycle of Hcsmogregarina muris Balfour, 1905, in it and in the 

 rat Mus decumanus. 



SUPERFAMILY B: IXODOIDEA Banks, 1894. 



Synonyms. — Acarus Linnaeus, ^6, pro parte ; Ricinice 'LdXreiW^, 

 1804, pro parte; Ixodides Leach, 1815; Ixodea Burmeister, 1837; 

 Ricini Koch, 1844 and 1847 ; Ixodes Gervais, 1844 ; Ixodida Kiichen- 

 meister, 1855; IxodidcB Leach, 1863; Ixodides Donnadieu, 1875, and 

 Megnin, 1876; Ixodes Wagner, 1876; Metastigmata CdJVQsiYim, 1892; 

 CynorhcBstea Marx, 1892; Arpagostoma Lahille, 1905. 



The term CynorhcBstea is derived from Aristotle, who speaks of 

 these arachnids as KvvopaL(TT7]s (the dog-tormentors), because ticks 

 were well known in his day to attack hunting-dogs. 



The Ixodoidea are the ticks, which have become of importance in 

 tropical medicine not merely because of their unpleasant bite, but 

 because of the spread of disease by their agency — as, for example, 



