Atycnl'tne, PutaijoniaUj and Cape Horn Muritlje. 187 



Colour al)ove olivaceous lined with Ijlack, the rump with a 

 (lull sull'iision of fulvous ; under surface dull greyish huH'y. 

 In true magellunicus the colour is more rufous ; but as both 

 of the only two availal)le skins have fornieriy been in sjiirit, 

 I hclieve that they are discoloured, and that no real difterence 

 exists. 



Dimensions of tlie type (measured in flesh) : — 



Head and body 100 mm. : tail 131 ; hind foot 29 ; ear IG. 



Skull : greatest length 27*5 ; condylo-incisive length 2 1'5 ; 

 iutcrorbital breadth 3 3 : upper molar s^eries 3'8. 



Hub. JSouthern Patagonia. Type from Koslowsky Vallev, 

 46° S., 71° W., Central Patagonia. 



Type. Adult male. B.M. no. 14.4.4.17. Collected 

 17th October, 1903, by J. Koslowsky. Presented by the 

 Buenos Ayres Museum. Other specimens received in 1903 

 direct from Mr. Koslowski. 



Specimens from the Rio Chica, Upper Santa Cruz, 

 measured by Dr. Allen, would appear to be intermediates 

 between the two forms ; but I am inclined to think that, if 

 only the fully adult specimens were included, the tail-length 

 would be as in the Koslowsky form, which is but little 

 further north in the same faunal area. 



On the other hand, aged specimens of true inagellanicus, 

 from Orange Bay in the far south, have the tail at most 

 115 mm. in length. 



The Cape Horn Akodon. 



As I have thus revised the determination of the Orange 

 Bay Euneomys and Oryzomys, I have thought it worth while 

 to re-examine the Akodon from the same locality, recorded as 

 ^'' Hesperumys {Habrothrix) olivaceus" in my paper of 1890*. 



As might be expected, this proves to be different from the 

 Akodon olivaceus of Chili, and is clearly referable to 

 A. xanihor/iimis, Waterh., of which it is, in fact, a topotype. 

 Orange Bay being in the Hardy Peninsula, where Darwin 

 caught the original example. A confusion in the labelling 

 of Darwin's specimens, recently corrected by Dr. Allen, and 

 a consequent misapprehension as to the size of adult xantho- 

 rhinus, was a contributory cause of the wrong determination. 



* Thomas, in Milne-Edwards, Miss. Scieut. Cap Horn, vi., Zuol., 

 Mamm. p. 28 (1890). The Murida; part of this work was written by lue, 

 and nu'iely translated in Paris. Its niisdeterminations, some of whicli I 

 lirtve now rectitied, are theref<ne not to be credited to my respcelt'd and 

 i'rieudly ally, Prof. Alphonse Milne-Edwards. 



