46 TJNGULATA. 



M. humboldti, but are distinguished in early stages of wear by the 

 presence of trefoils on only one column of each ridge (inner in upper 

 and outer in lower teeth), in consequence of the absence or small 

 development of the accessory tubercles on one side of the median 

 longitudinal cleft. The form of the dentine-disk on the columns 

 which do not present trefoils is pear-shaped, with the apex directed 

 towards the adjacent column. Cement is present in but small 

 amount; and the mandibular symphysis is produced into a long 

 deflected beak furnished with large incisors/ Premolars have not /./Voi. 

 been observed. In the second true molar the talon is so large as 

 almost to form a fourth ridge. 



Hob. South America (Chili, Bolivia, and Peru), Mexico l , and 

 Texas (No. 41652). 



41652. The third right upper true molar in an early stage of wear ; 

 from the Pleistocene of Texas 2 , U.S.A. This specimen 

 clearly exhibits the absence of a trefoil on the outer 

 column of the last ridge, and apparently agrees very 

 closely with the more worn specimen figured by P. Gervais 

 in the ' Mammiferes Fossiles de l'Amerique meridionale,' 

 pi. v. fig. 3 (1855). 



Toulmin- Smith Collection. Purchased, 1869. 



40988. Part of the left ramus of the mandible, containing nTT and 

 (Fig.) m.2 ; from the Pleistocene of Chili. This specimen is 

 figured by Falconer and Cautley in the ' Fauna Antiqua 

 Sivalensis,' pi. xl. fig. 15, the figure being copied in ' Fal- 

 coner's Palteontological Memoirs/ vol. i. pi. viii. fig. 2. 

 Both teeth are somewhat imperfect, and m. 2 is not pro- 

 truded ; the characteristic pear-shaped disks are exhibited 

 on the inner columns of m . l ; the hind talon of m . 3 might 

 be reckoned as a fourth ridge. The two teeth respec- 

 tively agree with the homologous specimens of the opposite 

 ramus figured by P. Gervais, op. cit. pi. v. figs. 4, 5. 

 Presented by the Trustees of the Canterbury Museum, 1868. 



20700 a. Fragment of a left maxilla without teeth, perhaps 

 belonging to this species ; from Texas. No history. 



1 Cope, Proc. Amer. Phil. Soc. vol. xxii. p. 5 (1884). 



2 The specimen does not agree with the description of the one tooth on which 

 M. serridens, Cope (Amer. JN T at. vol. xviii. p. 52j [1884]), from Texas, is founded. 



