384 
Biology of Phtliirus pubis 
Geographical distribution: The available data regarding the distri¬ 
bution of Phthirus are few, and I shall be grateful to any readers who 
may communicate information to me on the subject. Van Beneden 
(1889, p. 126) is certainly wrong in stating that crab-lice have “only 
been found on white races,” as the sequel shows: 
Europe: Crab-lice occur apparently throughout Europe, but so far 
I have only seen examples from England, France and Germany. The 
following records relate chiefly to specimens received.or examined by 
me. Asia: (N. 242) Nits taken from the eye-lashes of a Samper boy, 
aged 7, at Kasauli, India, 1917, by J. L. Mitter; the latter informs me 
that he tailed to find the active stages. Africa: (N. 219)^ from natives. 
Fort Jameson, N.E. Rhodesia, 1910, S. A. Neave; (N. 221)^ ditto, from 
Zomba, Dr H. S. Stannus, and (E)^ Blantyre, Nyasaland, 1910, Dr 
J. E. S. Old; (N. 220)^ from axilla of dog, S.E. shore of Lake Nyasa, 1910, 
S. A. Neave; Mr Claude Fuller informs me that the species occurs in 
Natal. Mr W. M. Aders (i. 1918) writes from Zanzibar that crab-lice 
are rare among African negroes owing to their cleanly habits; they shave 
their armj^its and pubes. They are found on negroes who allow their 
pubic hair to grow, and Mr Aders has taken them from various Indians 
including Parsees. Atmrica: (N. 74) from man, Baltimore, Md., U.S.A., 
1885, G. H. E. Nuttall; (N. 227) ditto. New Orleans, La., U.S.A., 1917, 
M. B. Mitzmain; (N. 238) from man and dog, from Panama, 1917, 
C. B. Williams. Mjoberg (1910, p. 171) records crab-lice from Cuba. 
Australia: According to Nicoll (1917, p. 280), who was stationed at 
Townsville, Queensland, the species is common in Tropical Australia. 
I. PREVALENCE AND MODES OF DISSEMINATION. 
Prevalence on Man. 
Reference has already been made to Greenough’s statistics (p. 84) 
wherein ca. 3 per cent, of verminous persons admitted to hospital in 
Boston, Mass., were found to harbour Phthirus, this figure representing 
their relative prevalence only. I have been unable to discover any 
record of their incidence on a population as a whole. It has been stated 
that the insect is more commonly present on individuals leading an 
active sexual life, and this may be true, since in the opinion of those 
best competent to judge, in most cases, infestation takes place through 
coitus. Prostitutes of the lower class are considered by like authority 
to be the most commonly infested class. On the other hand, owing to 
1 Received from the Imperial Bureau of Entomology. 
