8o Memoirs of the Indian Museum. [Vol. I., 1907.] 



the observations of Blanford, lyiston and myself, at least as far as regards Mus rattus alexandrinus. 

 This is not a rat that uniformly shows a light brown upper surface with light underparts as described 

 by Millais, but is a rat with an extreme range of colour from white through yellow and brown to black, 

 with a belly varying from lemon-white through orange-grey to almost black. What he seems to have 

 done is to separate the light and the dark varieties of the Alexandrine Rat, giving them respectively 

 the distinctive trinomen of alexandrinus and ater. That he is right in deriving Mus rattus rattus, the old 

 English Black Rat, from the original Alexandrine Rat no one can dispute who has read the extremely 

 interesting and convincing paper of M, de I'Tsle written in 1865.' This French naturalist, after 

 establishing his contention on the purely theoretical grounds of identity in morphology and habits, pro- 

 ceeded to prove it beyond dispute by a series of convincing experiments in interbreeding.^ 



The old English Rat or Mus rattus of France written of by de I'lsle is simply an occasional variety- 

 of Mus alexandrinus that has been fixed by climatic influences as a definite geographical race ; it is 

 now practically extinct and probably the real explanation of its rare reported recent occurrences are to 

 be explained by the occasional capture of specimens of Mus rattus ater, or in other words of black 

 specimens of Mus rattus alexandrinus. 



Conclusion. — 



Ihe final conclusion at which I arrive is that there is no distinction between the Mus rufescens and 

 Mus alexandrinus of India ; that both are identical with the Mus rattus of Great Britain, and probably 

 Europe ; that all should be known alike under the common specific name of Mus rattus ; and that the tri- 

 nominal nomenclature at present in vogue as regards M. rattus should be dropped as a non-scientific f allac3^ 

 These may seem bold words to be written by one who is but an amateur, but they are based on the moral 

 support afforded by the discovery, after this memoir was in the press, that my paper is little more than a 

 duplicate of that written fifty years ago by the FrenchscientistM.de I'Isle. The parallelism between the 

 two papers is extraordinär j' ; he decries the artificial manufacture of species, he deplores the reliance on colour 

 variations and minute differentiations, holds up to scorn the non- recognition of the characteristics of 

 immaturity, and generally where I have been satisfied with mildly protesting, openly denounces. The 

 following is a sample sentence : " Quelques naturalistes, MM. Brehm et Crespon par exemple, avaient 

 multiplié les types à plaisir, et même, en quelques genres, publiés à peu près autant d'espèces qu'ils 

 avaient d'individus entre les mains." This paper of M. de l'Isle's is distinguished by precise and 

 accurate observations and its clear and logical deductions, and is a mine of information to the natural- 

 ist who regards animals from a wider standpoint. I regret that I have come across it too late to incor- 

 porate it in my work, but I hope shortly to pubHsh a note on it in the Records of the Indian Museum. 



I De l'existence d'une Race Nègre chez le Rat, ou de l'identité spécifique du Mus Rattus et du Mus alexandrinus, Ann. 

 Sei. Nat. (v), Zool., Tom. iv, 1865, pp. 172 — 222, 



'^ My own experiments in breeding with Mus rattus failed. They were l<ept in a large aviary with some piebald domes- 

 ticated Brown Rats, and as the result, were soon killed by them. 



