ALLEN: mammalia: murid/E. 83 



larger forms. O. apicalis is an aberrant member of the group, as regards 

 its external characters, having non-fossorial claws and peculiar pelage. 



The present collection includes two species referable to Oxyniycfems, 

 namely, O. /anosiis Thomas and O. microtis Allen. They are both small 

 forms, with fossorial claws and small ears, with the teeth and general 

 form of the skull of the larger species of Oxymyctenis, but with very small 

 teeth and a relatively wider and less rounded zygomatic plate. The 

 single skull of O. /aiiosiis (the specimen was identified by Mr. Oldfield 

 Thomas) has no trace of an interparietal, which would thus seem to ally 

 it with Blarinomys. 



In the accompanying plates (PI. IX, Figs. 3-6, PI. X, Figs. 6-10), the 

 skull and dentition is presented, for convenience of comparison, of five 

 species of Oxymyctenis, including such diverse forms, as O. laiiosits, O. 

 microtis, O. inca, O. juliacce and O. apicalis. 



OxYMYCTERUS LANOSU? Thomas. 



Hesperomys [Habrothorix] xantJwrhinus Thomas, P. Z. S., 1881, 5, 



part ; only the specimen from Monteith Bay. 

 Oxymyctenis lanosns Thomas, Ann. & Mag. Nat. Hist. (6),' XX, Aug., 

 1897, 218. Monteith Bay, Straits of Magellan. 



Adult (February). — With a striking similarity to Akodon xaiithorJiiims 

 in size, proportions and coloration, but with much smaller ears, and softer 

 and much thicker pelage. Color above deep yellowish brown, varied 

 with blackish ; below grayish white ; nose not yellowish as in the A. 

 xantJiorhimts group ; upper surface of feet soiled yellowish white ; tail 

 bicolor, brownish above, whitish gray below ; ears small, slightly over- 

 topping the fur, scarcely different in coloration from the surrounding 

 pelage. 



Meas?irements. — Adult male: Total length, 127 mm.; tail vertebrae 

 (mutilated in life), 40; hind foot 20. Adult female: Total length, 145; 

 tail vertebrae, 55 ; hind foot 20. Skull, adult female : Total length, 24.6 ; 

 basal length, 21; greatest breadth; 11.8; interorbital breadth, 4; length 

 of nasals, 10; palatal length, 9.5; diastema, 6; palatal foramina, 5.2; 

 upper molar series, 3.5. There is no interparietal. 



This species is represented by only two specimens, collected on the 

 upper Rio Chico de Santa Cruz, in the Cordilleras, by Mr. Peterson, Feb. 

 10, 1897. Both specimens have been identified as this species by Mr. 



