1904.] RODENT DINOMYS BKANICKII. 161 



approaching steps of the keeper, it forms the resolution to 

 move with slow gait, expecting some food, evidently govei'ning 

 its movements as much by hearing and smell as by sight. It is 

 not easily irritated, and permits one to stroke and to scratch its 

 head and back, and only occasionally manifests its displeasure 

 by a low guttural growl. I have never yet observed a manifest 

 intention to bite. When let out of the cage it makes no attempt 

 to escape, and limits its excursions to an exploration of the 

 immediate neighbourhood in search of something to eat. It 

 occasionally scratches itself rapidly with its long claws, which is 

 the only occasion on which it manifests a capacity for rapid 

 movements when required. One thing not yet definitely verified 

 by us is its proclivity for digging, the development of the claws 

 at least leading to the supposition that the animal is well fitted 

 for that purpose. The amiable relations always existing between 

 mother and son prepossess one most favourably as to the natural 

 disposition of the animals *. 



This phlegmatic disposition seems to me to be a, very pi-ecarious 

 endowment for the struggle for life ; and considering the evident 

 advantages which result to the smaller domestic rodents, such 

 as rats and mice, from their nervously active constitution, it 

 would not be strange if the species should tend to disappear. 

 The apparent rarity of Dinomys may possibly find its explanation 

 in the consequences of such a psychological endowment in a more 

 nervous environment ; but it is also possible that this raiity is 

 because of the circumstance that the real habitat of the species 

 has not yet been clearly ascertained. As matters now stand, it 

 would be justifiable to suppose that the true home of Dinomys is 

 not properly in the Peruvian Andes, and that the first specimen 

 found there was merely a stray individual, and that its actual 

 habitat may rather be located in the almost unexplored regions 

 of the eastern slopes and tablelands of the Bolivian and Peruvian 

 foot-hills bordering on Brazil, including geographically the head- 

 waters of the rivers Acre, Puriis, and Jurua. I shall soon have 

 occasion to show that a scientific exploration of the region 

 above described will result in a multitude of great surprises 

 both from a zoological and a palfeontological point of view, of 

 which the interesting rediscovery of the lost Dinomys branickii is 

 only a first instalment. 

 Tara, 7th April, 1904. 



P.S. — Unfortunately, just before I send this note, the older 

 Dinomys, the mother, has died owing to a difficult parturition. 

 One foetus was born under normal conditions, while the other, 

 apparently on account of its abnormal position, could not be 



* After this portrayal of the aTiimal's peaceful character, it will not seem strange 

 that the account of the capture of the first individual in 1873 in the Peruvian 

 mountains, as furnished hy Prof. Peters, according to which it was deemed necessary 

 to deal two powerful sabre-strokes to lay the terrible monster low, always amuses 

 me. 



Proc. Zool. Soc— 1904, Yol. II. No. XI. 11 



