6 Memoirs of the Indian Museum. [Vol. I, 



GUIDE TO INDIAN RATS CONNECTED WITH PLAGUE. 



Of the 95 references given by Bonhote I have succeeded in finding no less than 

 68, the majority of them in the Hbrary of the Indian Museum, and a few in the 

 library of the Asiatic Society of Bengal. The most important of the references 

 which I have not been able to obtain are Miller's papers, in the Proceedings of the 

 Washington Academy of Science, deaHng with the rats found in the islands off the 

 coasts of Java and Sumatra such as M. tamhelanicus , M. lingensis, M. anamhce, etc. 

 The greater number of Bonhote's references are to rats found in Borneo, Sumatra, 

 Java, Celebes, the islands off the coast of Siam, and generally the islands of the 

 East Indian Archipelago, while rats from the Philippines are included, and even from 

 islands off the coast of China. Now, the rats of Luzon in the Philippines, as described 

 by Thomas in his very interesting paper on Mr. Whitehead's collection,^ form a group 

 which, so far as is known, have little connection with the forms found in India proper, 

 but which, on the other hand, show a distinct affinity to the Muridœ of Celebes 

 and Australia. So characteristic is the group that 5 new genera and 7 new species 

 have had to be framed to cover the new and strange forms found. It is clear then 

 that from the point of view of those who wish to take up the rats of India and their 

 connection with plague, much time would be wasted if they were to attempt to fami- 

 liarize themselves with the rats named in Bonhote's list. A still more serious objection 

 to using it as a basis for such work lies in the fact that the references apply solely to 

 the genus Mus, whereas the rats that are of practical interest to the Indian worker 

 may apparently belong to other genera. Thus I have already shown that the rat most 

 concerned with plague in Calcutta belongs to the genus Nesokia, namely Nesokia hen- 

 galensis^ ; and possibly as our knowledge of the subj ect increases, similar instances will 

 be found of rats, which though originally field rats, have become parasitic on man and 

 so have become liable to become carriers of plague. There must be many ready to 

 investigate the practical problem conveyed in the words " the rats of India and their 

 connection with plague," who would shrink from the much wider and more difficult 

 task involved in attempting to grasp the subtle differences and distinctions of such a 

 widely diffused and comprehensive group as the Oriental species and varieties of the 

 genus Mus. For the benefit of such it may be said that practically nothing has been 

 added to the list of Indian Muringe since Blanford wrote his Fauna of India in 1891. 

 In the twelve years that elapsed between the publication of this and the appearance of 

 the paper in Fasciculi Malay ensis, so far as I know, only one new rat has been added 

 to the Indian list. Mus vicerex, Bonhote ; and this, as will be shown later, is probably 

 only a synonym of Mus nitidus, or Mus pyctoris as it is named by Bonhote. That the 

 rats of India are still by no means worked out is indicated by my note on the Nesokia 

 from Jagdispur {postea, p. 43), but all the species so far named will be found in Blan- 

 ford' s work, with the exception above given, namely M. vicerex. As noted by Bon- 

 hote, the most important papers in connection with the Mus rattus group are : — 



Trans. Zool. Soc, vol. xiv, 1895-1896, p. 377. ^ Cahiitfa Plague Report., 1905-1906. 



