11 "4" ME. OLDFIELD THOMAS OX [Feb. 18, 



external margin of the blade, so that a valley is formed between 

 the inner and the outer part of the tooth. 



By the conformation of its upper carnassial, therefore, the fossil 

 is excluded from the Melince — the upper and the lower one making 

 only a slight approach towards the form they have in some 

 members of this subfamily ; whilst the characters of the skull and 

 of the skeleton, so far as known, bring it likewise in closer con- 

 nection with the Mustelitue and with Mustela in particular. To 

 emphasize this, it seems preferable to leave it in the latter genus, 

 viz., to revive the name by which it was originally described — 

 Mustela palceattica Weith. 



EXPLANATION OF PLATE VIL 



Sknll of Mvstela palceattica Weitli., from Pikenni ; Geological Museum, Turin. 



All figures of the natural size. 



FTg. 1. Side vieAT. Fig. 2. Upper view. Fig. 3. Lower view. Fig. 4. Posterior 

 upper premolar and molars, right side. Fig. 5. Lower true molars and 

 posterior premolar, right side. 



2. On Two new Genera of Rodents from the Highlands of 

 Bolivia. By Oldfield Thomas^ F.R.S. 



[Received January 28, 1902.] 

 (Plates VIII. ct IX.^) 



Mr. Perry O. Simons, the collector who lias been doing such 

 admu-able work in the Andean chain, and to whose efforts we 

 owe the discoveiy of a very lai-ge number of the mammals of that 

 interestmg region, has now sent home a collection from the high 

 grounds of South-western Bolivia, from the Depai'tments of 

 Oruro, Potosi, and Sucre. Among these, besides some new species 

 of known genera, described elsewhere, there are examples of two 

 rodents so distinct as to demand generic separation, and I have 

 therefore thought them worthy of being brought before the 

 Society for description and illustration. 



Neoctodox, gen. nov. {Octodontidce.) 



Tail comparatively bushy. Palms aiid soles granulated, the 

 pads imperceptible. 



Palatal foi-amina longer than in Octodon, the actual openings, 

 instead of only the outer fossa, penetrating into the maxilla?. 



Incisors smooth, comparatively thick antero-posteriorly, theii^ 

 depth rather more than 1^ their breadth, as compared with about 

 1^ in Octodon. 



Molars rootless, simpler than in Octodon, with a slight concavity 

 on their outer side and none on the inner, there being no trace 



1 For explanation of the Plates, see p. 117, 



