478 On new Species o/Reitlirodon dr. from Argentina. 



blackish, little browner on the rump, sides dark slaty grey, 

 abruptly clianp^ing halfway down to the greyish white (some- 

 times tinged with bufty) which covers the whole of the under 

 surface and inner sides of the limbs, tliough the hairs are 

 everywhere slaty greyish at base. Crown black. Ears 

 thickly hairy, dark brown, the proectote blackish. Upper 

 surface of hands and feet whitish, often with darker meta- 

 podials. Tail heavily haired, the hairs below longer than 

 those above, so as to form a swimming fringe; blackish 

 brown above, lighter brown, sometimes even dull whitish 

 below. 



Dimensions of the type: — 



Head and body 168 mm, ; tail 154: ; hind foot 36 (with 

 claws 39, therefore barely 1^ inch English, and decidedly 

 less than 1^ inch French or German) ; ear 22'5. 



Skull : greatest length 39 ; condylo-incisive length 37"2 ; 

 zygomatic breadth 19 ; Jiasals 15 ; inteiorbital breadth 6 ; 

 breadth of brain-case 16; zyo^omatic plate 3*7; palatilar 

 length 17*3 ; palatal foramina 8*8 ; upi)er molar series 6'4. 



Hah. Islands of Parana delta. Type from Isla Ella, other 

 specimens from Los Cisnes, Rio Carabelas. 



Type. Adult male. B.M. no. 17. 6. 1. 6. Original num- 

 ber 2843. Collected 15th February, 1917, by li. Kemp. 

 Presented by Old Held Tliomas. Fifteen specimens obtained 

 by Mr. Kemp and eight by Mr. II. E. Box. 



Besides its difference in size, Lichtenstein's animal appears 

 to have had nothing like the extent of the whitish on the 

 under surface so prominent in S. aquaticxis, where the white 

 rises nearly halfway up the sides. In tomentosns no white is 

 shown in the plate, and the description runs " Mitte der 

 Bauchseite matt ascligrau." A casual note of my own ou 

 the type in Berlin says " belly but little lighter," so there is 

 certainly nothing of the striking bicolor coloration charac- 

 teristic of S. aqnniicus. 



This is one of the interesting delta animals which, in order 

 to carry on at all, have either to swim or climb, for their 

 habitat is com])letely flooded whenever the waters of the 

 La I'lata estuary are banked up by the south-east wind. 



