PART II. INSECTIVORA. 



At the present time continental South America contains no representa- 

 tive of the Insectivora. Unusual interest therefore attaches to Ameghino's 

 discovery of the genus Necrolestes in the Santa Cruz beds, which was an- 

 nounced in 1891. In his first account Ameghino suggested that this 

 curious fossil had analogies with the Cape golden moles of Africa (Chry- 

 sochloridce], but in a second paper (1894) this suggestion is not repeated 

 and the genus is referred to a new family, the Necrolestidce. The material 

 collected by Messrs. Hatcher and Peterson adds largely ^to our knowledge 

 of this genus and the result of a comparison with the skeletons of Chry- 

 sochloris and the Marsupial Notoryctes is to confirm Ameghino's original 

 suggestion of a relationship between the African genus and Necrolestes. 

 The new family name is, however, provisionally retained, because it would 

 be premature, and perhaps entirely misleading, to refer the fossils to the 

 existing family. 



NECROLESTIDsE. 



NECROLESTES Ameghino. 



(Plate LXIV, Figs. 1-5.) 



Necrolestes Amegh. ; Rev. Argent, de Hist. Nat, T. I, 1891, p. 303. 



The dental formula is If, Cf, Pf, Mf . In the upper jaw the incisors 

 diminish in size, though not regularly, from the median to the lateral one ; 

 i- is nearly and sometimes quite as large as \-, while i 4 is smaller and i- 

 considerably smaller than the anterior pair ; i 1 is slightly recurved and 

 antero-posteriorly compressed, giving it some resemblance to a very short 

 rodent tooth, while the others are laterally compressed. Viewed from the 

 outer side, the crowns of all the incisors have a rectangular, almost square 

 shape and those of i 1 and - are faintly grooved ; each incisor is carried on 

 a single fang. In Chrysochloris the incisors are three in number ; \- is much 

 enlarged and i^ and especially i a much reduced ; the crowns are acutely 

 pointed and minute accessory basal cusps are present in some of the 



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