C. Strickland and G. ]Mekriman 
17 
Summary. 
To summarize our principal observations made in the course of the 
investigation into the rat-fleas of the suspected plague area of East 
Suffolk, July—October, 1911 : 
(1) We found an average of four fleas per rat : 822 rats were 
examined and 3293 fleas taken. 
(2) The average was subject to a local variation (0‘6 to 6‘5). 
(3) 15 species of fleas were taken from the rats, but of these there 
were only two species, 0. fasciatus and G. agyrtes, which occurred in 
any numbers. 
There were C. fasciatus 1986 or about 60 per cent. 
G. agyrtes 1257 „ 38 „ 
Rare species 50 „ 2 „ 
(4) The average number of fleas per rat and the percentage of rats 
infested by fleas showed a well-marked seasonal variation, there being 
a considerable decline in the numbers as the cooler weather came on. 
Geratophyllus fasciatus and Gtenophthalvius agyrtes both participated in 
a similar way in this variation. 
(5) G. fasciatus is chiefly found on rats caught near human habi¬ 
tations ; G. agyrtes on those caught in the hedgerows. 
In conclusion, we wish to tender our best thanks to all those gentle¬ 
men who have helped us in our work. Prof G. H. F. Nuttall, F.R.S., 
very kindly aided us in organising the work and in the revision of our 
manuscript; Dr A. Eastwood, on behalf of the Local Government 
Board, placed at our disposal the material upon which we made our 
observations ; Dr A. Pringle, Medical Officer of Health for Ipswich, 
kindly supplied us with the meteorological records of that town ; Mr 
C. J. Huddart, in his administrative capacity, gave us much assistance; 
and the Hon. iST. Charles Rothschild confirmed some of our determina¬ 
tions. 
REFERENCES. 
Bose d’Antic (1801). Bull. Soc. Philom. ii. 156. 
Bought (1835). iVov. Ac. Leap. Carol, xvii. 507 
Chick and Martin (1911). Journ. of Hygiene., xi. 122. 
Curtis (1826). Brit. Ent. in. 114. 
- (1832). Ihid. IX. 417. 
Dale (1878). History of Glanville's Wooton. 
Uajipp. (1910). Zool. Jakrh. Suppl. 12, 620, 622. 
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