224 THE DESEADO FORMATION OF PATAGONIA 



Measurements, Specimen 3020 



Lower dentition, premolar 3, length 1 mm. 



Lower dentition, premolar 4, length 5 mm., width 2 mm. 



Lower dentition, molar r, length 4 mm., width 2 mm. 



Lower dentition, height under pra. 4 6.5 mm. 



Caenolestinae 



The subfamily is distinguished by the formula -- J 43 , 

 pm. 4 not being enlarged, and the lower molars being 

 tuberculo-sectorial. In the Deseado formation this group 

 is only represented by a single species, based on a single 

 tooth found by Ameghino. 



Pseudhalmarhiphus guaraniticus Ameghino 



P. guaraniticus Amegh., 1903, Anal. Mus. Nac. Buenos Aires, ser. 3, t. 2, p. 

 S3- 



Based on a single tooth, similar to those found in the 

 Santa Cruz. 



Abderitinae 



The subfamily is distinguished by the formula J \ ? 2 ? 3 , 

 the fourth premolar being enlarged into a sectorial tooth 

 on the sides of which are vertical striae. The molars are 

 buno-lophodont. The Deseado has yielded only a tiny 

 form, designated Parabderites, which differs from the Santa 

 Cruz genus Abderites in pm. 4, the same shape, by with 

 few to no striae on its sides. 



Parabderites minusculus Ameghino 



P. minusculus Amegh., I902, Bol. Acad. Nac. Cienc. Cordoba, t. 17, p. 43. 



The species as described by Ameghino is based on a 

 lower jaw with pm. 3 to m. 3. The specific character is 

 the lack of striae on pm. 4. No figure is given but the 

 following measurements indicate the size. 



Lower dentition, premolar 3 to molar 3 9 mm. 



Lower dentition, height of mandible under pm. 4 4 mm. 



