COLLECTIONS IN MALAYA 
21 
No rickettsial infection was recovered from about 300 larvae of the vector from this 
island. In the circumstances, this negative result is surprising and demands further investi- 
gation. 
Bat cave on Pulau Seletan. — The twin rocky islets Angsa and Seletan, near Port Swetten- 
ham, were visited on the return journey and a number of Tomb Bats ( Taphozous melancpogon ) 
were shot. Some of these were infested by Trombicula taphozous Worn., T. insolli Philip & 
Traub, and a few specimens of T. deliensis. 
Nicobar Islands 
(14 days — October, 1950) 
Arrangements were made in 1950 for collections to be made in Car Nicobar where there 
were several scrub-typhus casualities among Japanese troops in 1944. We are very grateful 
to the Government of India for permission to do this, and to the Royal Air Force, who have 
a station on the island, for their collaboration. In October, 1950, Dr. C. A. Gibson-Hill of 
the Raffles Museum spent a fortnight on Car Nicobar and the very interesting collection he 
made on behalf of the unit was received in 1951. 
Dr. Gibson-Hill trapped widely both in the scrub which covers much of the island and 
in the huts of the islanders, catching 76 rats in all. The 24 rats from the huts, which were 
beehive-like structures raised on poles, were of a pale-bellied form of Rattus rattus. Of the 
52 rats trapped in scrub, grassland, and R.A.F. camp, and the island store or shop, 51 were 
of a dull-bellied form of Rattus rattus , and one was a R. rniilleri of a slightly smaller size than 
that common in Selangor. The identification of the R. mulleri has been confirmed by Sir 
John Ellerman. 
It is noteworthy that the distribution of the pale and dark-bellied forms of Rattus rattus 
reversed the usual order. In Malaya, as in most countries, the dark-bellied form (R. r. diardii ) 
is a house-rat and the pale-bellied form ( R . r. jalorensis ) does not enter houses. The dark- 
bellied scrub rat of Car Nicobar is perhaps analogous to the dark-bellied R. r. jarak of the 
forest floor of Jarak Island (probably a feral house-rat), and the pale-bellied rat of the stilt- 
houses is probably analogous to the white-bellied R. r. khyensis of Rangoon, which although 
primarily a garden tree-rat does enter houses, there apparently being no dark-bellied R. rattus 
to compete with it. 
Only two species of trombiculid mites were found on these rats. The vector Trombicula 
deliensis , was common on the pale-bellied rats from stilt-huts (nine out of 24 rats bore 440 
vector mites). This compares with the heavier infestations found on the wood-rat R. r. jalo- 
rensis in Selangor. Of five dark-bellied rats trapped in the island “store” two were infested 
by 4 T. deliensis and 22 Euschongastia indica , which is the dominant mite on house-rats in 
Selangor. 
Summary 
1. A routine collection of over 21,000 vertebrates, made in Malaya between 1948 and 
1952 by the Colonial Office Scrub Typhus Research Unit, comprised some 115 species of 
mammals, 30 species of birds, and 90 species of reptiles and amphibians. The collecting 
areas are here described, and also the method of collection both of the animals and of their 
external and internal parasites. 
2. A brief account is given of the principal hosts and their habitats. 
3. The distribution of the principal species of trombiculid mites on these hosts is shown 
in some detail, and gross infestation figures are given for the major groups of ectoparasites. 
4. A brief account is given of additional small collections from two localities on the 
mainland, from islands in the Malacca Straits, and from the Nicobar Islands. 
MALAYA , No. 26, 1953 
