290 
Observations on Wild Rats in England 
animals. In each case the findings were placed in tubes which were labelled 
with a number corresponding to that of the host. At a later date the ecto¬ 
parasites were determined. A post-mortem examination of the rat was then 
performed. Films were prepared from the heart blood. The alimentary tract 
and urinary bladder were removed and searched for helminths. Specimens 
of the intestinal contents were examined for protozoa, any macroscopic 
abnormalities were noted and, if necessary, portions of the internal organs 
were taken for section-cutting and staining. 
Ecto-Parasites. 
(i) The following were found: 
On 34 black rats 
On 444 brown rats 
Parasite 
Per cent. 
Laelaps echidninus Berl. 
52-9 
Haematopinus spinulosus Burin. 
44-2 
Xenopsylla cheopis Roths. 
5-9 
Parasite 
Per cent. 
Laelaps echidninus Berl. 
24-1 
Notoedres notoedres Megn. 
0-2 
Haematopinus spinulosus Burm. 
11-3 
Xenopsylla cheopis Roths. 
3-6 
C eratophyllus fasciatus Bose. 
3-2 
CtenophtJialmus aejurtes Heller 
0-9 
Ctenocephalus felis Roths, vel 
canis Curtis 
0-2 
Helminths. 
The following intestinal forms were found: 
In 34 black rats Parasite 
Hymenolepis diminuta Rud. 
„ nana-fraterna Stiles 
„ longior Baylis ... 
Oxyuris obvelata Rud. 
Per cent. 
17-6 
17-6 
32-4 
3 
In addition Trichosomoides crassicauda Bell was found on three occasions 
in the urinary bladder but as only a small number of black rats were examined 
for the presence of this parasite it w r ould serve no purpose to state a percentage. 
In 430 brown rats the intestinal worms w ? ere as follows: 
Parasite 
Per cent. 
Hymenolepis diminuta Rud. 
28-4 
„ nana-fraterna Stiles 
1-2 
,, longior Baylis ... 
24-9 
Heligmosomum braziliense Trav. 
8-6 
„ vexillatum Hall 
0-2 
Viannaia ? sp. incert. 
0-7 
Capillaria annulosa Dujardin 
0-4 
1 richosomoides crassicauda Bell was found in the bladder of 48’3 per cent, 
of 333 rats examined. 
The unidentified ova (av. measurements 75/x x 39*7 p.) of an unknowm 
worm were seen in the intestinal contents on three occasions. As no corre- 
