72 PATAGONIAN EXPEDITIONS : ZOOLOGY. 



about January i, 1898, at Punta Arenas, of which 7 are adult and 3 im- 

 mature. Only one of the adults has measurements or is marked for sex. 

 The species is entirely unrepresented in the large series (about 100 speci- 

 mens) of Akodonts collected by Colburn and Peterson in the Santa Cruz 

 region of Patagonia, and I very much doubt whether it is found there. 



These specimens are all in thin summer pelage, and are thus compar- 

 able with the gray phase of A. canesceris, which is the corresponding sea- 

 sonal pelage of that species. They are thus readily distinguishable in 

 coloration when specimens of corresponding seasons are compared, but 

 summer specimens of A. xaiitliorJiimis have a general resemblance in 

 coloration to winter specimens of A. canescens. But A. xanthorliiuus is 

 much the larger animal, although the proportions are similar. The skull, 

 however, is not only larger (averaging about 3 mm. longer), but has the 

 rostral portion of the skull relatively much more attenuated, it being more 

 than one half of the basal length of the skull instead of less than one 

 half, as in A. canescens. These specimens agree with Waterhouse's 

 description and type, and there can be no question of their correct iden- 

 tification. 



In the original description of ^. xanthorhinus [I. c.) the type locality is 

 given as "Santa Cruz," but in the "Voyage of the Beagle" (/. c.) it is given 

 as " Hardy Peninsula, Tierra del Fuego," where also Darwin states : "This 

 species was caught on the mountains, thickly covered with peat, of Hardy 

 Peninsula, which forms the extreme southern point of Tierra del Fuego." 

 This seems to settle the case beyond question that Hardy Peninsula and 

 not Santa Cruz is the type locality of A. xanthorJiinus. Mr. Waterhouse 

 further says (/. c, p. 55): "The specimens of this animal \M. xantho- 

 rhinus\ are both from Patagonia ; one of the specimens oiMiis xanthorhinus 

 was brought by Mr. Darwin from Tierra del Fuego ; and as the other 

 formed part of Captain King's collection, it in all probability came from 

 the same locality." 



Waterhouse had, curiously, an old and young specimen each of Mus 

 xanthorhinus and M. canescens; of the former one specimen is still ex- 

 tant in the British Museum, but the other seems to have been lost, although, 

 as noted below (p. 73), both specimens oi M. canescens still remain. The 

 specimen of yJ/. xanthorhinus is B. M. No. 55-12-24-156, and is labelled 

 " Hardy Peninsula, Ex. Coll. C. Darwin," and should of course stand as 

 the type. 



