242 Mr. 0. Thomas on Mammals from 



continuance over the rump and on to the sides of the tail, 

 from C. huniboldti by its coarser fur, and from all except 

 C. humboldti and snffocans by the two-coloured hairs in its 

 heavily tufted tail. 



I have named this fine animal in honour of Mr. Ernest 

 Gibson, to whose help and hospitality the making of this 

 interesting- collection is due. 



" Caught in hollow tree in monte." — C. II. B. G. 



6. Ilolochihis darwini, Thos. 



S. 2109 (imm.) ; ? . 2108, 2110 (yg.). 



In spirit from Mr. Gibson's collection — two males, 62 a 

 and />, immature and very old respectively. 



The old male skull taken from 62 b shows a remarkable 

 superiority in size over the adult female, 2108, but the differ- 

 ence seems to be characteristic of some at least of the species 

 of this genus. Darwin's type from Bahia Blanca is a female. 



All the specimens agree in having fulvous bellies, and 

 differ therein from the Panama and La Plata H. vulpinus. 



7. Oryzomys flavescenS) Waterh, 



<?. 2053; ?. 2052. 



" Trapped in hollow tree in monte." — C. II. B. G. 



8. Eligmodontia laucha, Desm. 

 ? . 2102. 

 '*• Caught in esparto grass." — C. II. B. G. 



9. Akodon arenicola, Waterh. 



? . 2111, 2112. 

 " Burnt out of reed-bed."— C. H. B. G. 



10. Ctencmys talarum antonii, subsp. n. 



S . 2060, 2080, 2081 ; ? . 2062, 2067, 2068, 2071, 2079, 

 2107, 2113. 



Adult and two young in spirit. 



Longer tailed, paler, and with more white on the under 

 surface than in true talarum. 



Size as in talarum. Colour of head and back generally 

 paler, most specimens near " isabella," the dorsal area little 

 blackened. In talarum the dorsal hairs are heavily blackened 

 terminally and the frontal region is prominently deep black, 

 this colour being only present in one out of the ten Ajd 



