362 Mr. O. Thomas on some 



rufous than that, especially on the last-named part. Through- 

 out the colour is made up of a finely grizzled mixture of grey, 

 black, and yellowish in varying proportions. Head con- 

 colorous with back. Under surface dirty yellowish white, 

 the bases of the hairs slate-coloured. Ears small, well-haired, 

 brown, with a slight admixture of yellowish. Upper surface 

 of hands and feet brownish white. Fifth hind toe short, 

 barely reaching to the base of the fourth. Tail short, dark 

 brown above, dirty fulvous below. 



Skull evenly convex above in profile, with a short muzzle 

 and long narrow brain-case. Supraorbital edges sharply 

 beaded, even slightly overhanging, and forming slight angular 

 postorbital processes. Interparietal small. Palatal foramina 

 long, nearly twice the length of the molar series. Molars 

 apparently of normal Acodon structure, but too much worn 

 in the type for accurate description. 



Dimensions of the typical skin : — 



Head and body (stretched) 132 millim. ; tail 71 ; hind foot 

 (moistened) 22 ; ear (dried) 14. 



Skull : length from just above foramen magnum to tip of 

 nasals 29*6; greatest breadth (c.) 15; nasals, length 10*5; 

 interorbital breadth 4'8 ; interparietal, length 2, breadth 5*5 ; 

 outer wall of foramen magnum 3'4 ; diastema 8'5 ; length of 

 palatal foramina 7 ; upper molar series 4*2. 



Hah. Ecuador (probably Pallatanga). Coll. L. Eraser. 



Type-. BM. No. 59.11.1.8. 



This peculiar-looking species is of somewhat doubtful 

 position, as its comparatively short crisp fur and, especially, 

 its beaded supraorbital edges separate it widely from any 

 other Acodon. In fact I think it is nearly certain hereafter 

 to require generic or subgeneric separation ; but this can only 

 be done when our knowledge of the whole group is much 

 further advanced than it is at present. It is, however, possible 

 that, in company with some other beaded species which have 

 been referred to Acodon on account of their external propor- 

 tions, such as A. lasturus, Lund, A. punctulatus should 

 properly be placed in Oryzomys^ of which it and they would 

 then form a special group of short-tailed species. 



Acodon macronyx, sp. n. 



Similar to A. megalonyx^ Waterh., in size, general propor- 

 tions, and especially in the enormous development of the 

 claws. It differs, however, by its much more greyish general 

 colour, which matches Ridgway's " hair-brown," more 

 whitish under surface, and by its shorter, broader, heavier, 



