148 



PATAGONIAN EXPEDITIONS: PALEONTOLOGY. 



Theosodon garrettorum sp. nov. 



(Plates XVI; XVII, Figs, i, 2, 5 ; XVIII, Figs. 2, 4, 4a, 6, 8, Sa, 10; XIX, Figs. la, 2, 



5-7 ; XX, Figs. 2, 5, Sfl.) 



This species is of very nearly the same size as the preceding one, but 

 differs from it in a number of well-defined characters. The type-specimen 

 is the nearly entire skeleton (No. 15,164) figured in Plate XVI, though 

 completed with some addition of missing details from other species. The 

 name is given in honor of Messrs. John W. and Robert Garrett, of Bal- 

 timore, whose generosity has been one of the mainstays of the Patagonian 

 expeditions. 



The permanent dentition is essentially similar to that of T. lallemanti, 



but there is no cingulum between the inner cusps of the upper molars and 



ml is more reduced in size, and in pg the anterior inner fossa is not so 



deeply concave. 



Measurements. 



M^, width . 

 Ig, major diameter 

 " minor diameter 

 Ig-, major diameter 



Upper dentition, extreme length 

 IJ-, major diameter 



" minor diameter 

 I-, major diameter 



" minor diameter 

 I^, major diameter 



" minor diameter 

 Upper canine, ant.-post. diameter 

 " " transverse diameter 



Upper premolar-molar series, length 



" premolar series, length 

 pi, length {i. e., ant.-post. diam.) 



" width {i. e., greatest trans, diam, 

 P^, length . 



" width . 

 P-^, length . 



" width . 

 P^, length . 



" width . 



Upper molar series, length 

 Mi, length . 



" width . 

 M^, length . 



" width . 

 M-^, length . 



.190 



.010 



.006 



.011 



.008 



.011 



.008 



.0125 



.009 



•137 



.074 



.015 



.009 



.0165 



.016 



.018 



.018 



.0195 



.020 



.063 



.020 



.0225 



.0225 



.024 



.0195 



" minor diameter 

 Lower canine, major diameter 

 " " minor diameter 



Lower premolar-molar series, length 



" premolar series, length 

 Py, length 



" width 

 P^^, length 



" width 

 P^, length 



" width 

 P^, length 



" width 



Lower molar series, length 

 My, length 



" width 

 Mg, length 



" width 

 Mj, length 



" width 



.019 



.013 



.0085 



.013 



.0085 



.014 



.009 



.140 



.070 



.015 



.009 



.018 



.0095 



.021 



.012 



.022 



•013s 



.070 



.0225 



.015 



.023 



.019 



•023 



.015 



The milk-dentition of this species is not definitely known, but a frag- 



