IGO Mcrriam — Neiv Gemis cmd Sjm-ies of Murine Rodent. 



Ijeads like Xi/rljniii/s, large laclirvnuils, a large interparietal, and 

 large and greatly inflated audital l.)ulla', which differ from tliose 

 of any murine with which 1 am acquainted and resemble those 

 of some of the carnivores. \n dentitiDU it coml)ines tlie o-rooted 

 U])])er molars of the true murines with the non-tuhercular pris- 

 matic grinding crowns of the arvicolines, and has the l)roadh^ 

 rounded alternating closed triangles of Pheadcomys, only e\'en 

 more crowded. 



The new genus may be cliaracterized as follows: 



Xenomys •■ yon. iiov. 



Skull resembling that of Ncotonia in general form and a})pear- 

 ance, but differing in possessing marked elevated and laterally 

 projecting supraorbital beads, much larger and heavier lach- 

 rymals, greath' enlarged and inflated audital l)ulhe, Avhich are 

 elongated antero-j^osteriorly and ]>arallel to the axis of the skull 

 and to each other, instead of being set obliquely as in Xcotoma 

 (in which genus they would meet in the middle of the })terygoid 

 fossa if produced forward along their strongly convergent axes). 

 The anterior border of the s(|uamosal a1 )ove the zygomatic pro- 

 cess is marked by a projecting vertical ridge corresponding to 

 the postorbital process of Canicuhs, Myodes, and Pheiiacoinys, and 

 serving to indicate the separation of the (small) temjioral Irom 

 the (large) orl)ital fossa. Posteriorly the s(iuamosal does not 

 reach the occi])ut as it does in Xeotoma, but ends aliout half-way 

 between the posterior root of the zygoma and the occii)ut. Its 

 l)Osterior spicule reaches the mastoid. The paroccipital })ro- 

 cesses are long and stout. The interi)arietal is very large and 

 somewhat diamond-shaped. The condyloid })rocess of the mandi- 

 ble is long and slender and higher than the coronoid process. 



Dented Characters. — Molars truly rooted ; the roots closed at the 

 tips ; upper molars 3-rooted ; lower molars 2-rooted. First upper 

 molar with anterior and posterior roots subcylindric and a Ijroad 

 flat root in the middle on the inner side, the latter slightly 

 notched at the tip and having the appearance of two roots grown 

 together. Between the middle and posterior root in the speci- 

 men examined is a small needle-like auxiliary or supplemental 

 root about half the length of the others ; middle upper molar 

 with 2 anterior and 1 [)Osterior roots, the anterior on the inner 

 side about double the size of the others ; last upper molar with 



* X'ni()iii!/!<: fVdiii ^;'."'9, strange, and ,"-''<', mouse. 



