1909.] R. E. Lloyd : The Races of Indian Rats. 55 



Not a single specimen of Mus decumanus was obtained. It 

 is difficult to assert that this rat, which is so common in other Indian 

 ports, does not occur in Madras city. The evidence of its absence 

 however, seems almost conclusive. 



Some hundreds of rats were being received daily during several 

 months. From these one specimen of a greyish short-tailed rat 

 was sent to the Madras Museum suspected of being Mtis decumanus. 

 This was examined b}^ the writer, the skull being removed. It was 

 obvioush' a Gunomys. 



The rarity or absence of Mus decumanus can, however, be ex- 

 plained. The port of Madras differs from the other great ports of 

 India. Long lines of wharves with steamers moored alongside 

 are conspicuous features of the ports of Calcutta, Bombay and 

 Rangoon. In the smaller port of Madras the conditions are different 

 and steamers usually unload their cargoes at a jetty or by means of 

 small boats. These conditions would deter the ships' rats from in- 

 vading the shore in great numbers, but could not prevent the 

 invasion altogether. A more potent factor in determining the 

 suppression of Mus decumanus awaits those that reach the 

 shore. 



These large rats are well known as dwellers in the drains and 

 outhouses of the ports of India, where they can sustain themselves 

 in competition with other species. In Madras, however, they 

 meet, to their detriment, with a larger and still more formidable 

 race, the bandicoots, whose mode of life is remarkably like their own. 

 A similar explanation may be given of the comparative scarcity of 

 Mus decumanus in Rangoon, for in that city the large mole-rat 

 Gunomys varius, which was spoken of as " bandicoot" by the rat- 

 catchers, is the common out-door rat. This race would compete 

 successfully with Mus decumanus in the same manner though not 

 with such complete success as the Madras bandicoot, for in the 

 struggle the two races would be on more equal terms. In Calcutta 

 and Bombay, Mils decumanus thrives with little competition. The 

 bandicoots of Calcutta are rare and live in burrows after the manner 

 of field rats, especialh^ around the numerous tanks of that city. 

 That competition and enmit)^ between the different races of rats 

 actually exists will be shown later (Appendix III). • ■ 



Mds. I, Mus rattus — 



The rats of this group were examined somewhat superficially, 

 few measurements being recorded. On inspecting a large number of 

 them the general impression was received that they were some- 

 what smaller than the rats of other parts of India. The few 

 measurements that were made confirmed this impression. It is not 

 unlikely that the mean length of the race in Madras city is as low 

 as 160 mm. or i cm. less than that of the race found on the west 

 coast of Madras. 



They were on the whole less variable than the western race. 

 Melanotic and white-bellied varieties were not met with. 



